Biology

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by  BarCharts, Inc.

BarCharts, Inc.® WORLD’S #1 ACADEMIC OUTLINE
Evolution, cytology, energy & life, cell transport, cell reproduction, organismal reproduction & meiosis, genetics & Mendel, molecular & population genetics
Basic concePts cytoloGy: the study of cells
1. Biology is the study of life Cell Theory Eukaryotic Cells
2. The characteristics of life are metabolism, reproduction, All living things are composed of cells and come from Eukaryotes have a complex cellular organization;
growth, movement, responsiveness, and complex cells membrane-bound organelles, located inside the cell
organization 1. Cell size: Small to maximize the ratio of surface membrane, include the following:
3. The scientific method: How scientists study biology area to volume for regulating the internal cell
1. Nucleus: Contains DNA in the form of chromosomes;
A. Based on the observation of phenomena to environment
controls cellular activities via genes
formulate hypotheses that are both testable and 2. Cell (plasma) membrane: Composed of a fluidlike
falsifiable (in case they are wrong) phospholipid bilayer, proteins, cholesterol, and 2. Nucleolus: Located within the nucleus; site for
B. Used to test hypotheses, collect data, and analyze glycoproteins ribosome synthesis
data statistically (if necessary) Cell (Plasma) Membrane 3. Rough endoplasmic reticulum: Has ribosomes,
which are necessary for protein synthesis
Glycoprotein 4. Smooth endoplasmic reticulum: Involved primarily
evolution Outside cell
in lipid synthesis, as it lacks ribosomes
Evolution is the concept that all organisms are related to 5. Golgi apparatus: Packaging center for molecules;
each other by common ancestry; it is the unifying theme synthesizes carbohydrates
in biology 6. Lysosome: Contains hydrolytic enzymes for
1. Natural selection: A mechanism, formulated by 19th- intracellular digestion
Phospholipid
century biologists Charles Darwin and Alfred Wallace, bilayer 7. Peroxisome: Involved in hydrogen peroxide synthesis
for the occurrence of evolution based on the survival and degradation
of those offspring best adapted to the conditions in
8. Chloroplast: Site of photosynthesis
which they live
9. Chromoplast: Contains nongreen pigments
A. Individuals sexually reproduce, creating many Inside cell 10. Leukoplast: Stores starch
more offspring than could possibly survive Cholesterol Channel protein 11. Mitochondrion: Produces adenosine triphosphate
B. These offspring are not identical (in most situations)
but show variations based on genetic differences 3. Cell wall: Outside of the cell membrane in some (ATP)
C. Essentially, those individuals with variations that organisms; composed of carbohydrates (e.g., 12. Vacuole: General storage and space-filling structure
allow them to survive (i.e., adaptations) to the age cellulose for plants; chitin for fungi) or carbohydrate Animal Cell
derivatives (e.g., peptidoglycan for bacteria)
of reproduction can pass their genes on to the next
4. Cytoplasm: Material outside the nucleus
generation
A. Site for metabolic activity
D. Thus, nature is selecting offspring and shaping the
B. Cytosol: Solution with dissolved substances
evolution of species
such as glucose, CO, O, etc.
Organismal Evolution 2 2
C. Organelles: Membrane-bound subunits of cells
with specialized functions
KINGDOM KINGDOM KINGDOM 5. Cytoskeleton: Supportive and metabolic structure
PLANTAE FUNGI ANIMALIA
composed of microtubules, microfilaments, and
intermediate filaments
Cytoskeleton
Microfilaments
Microtubule Plasma Endoplasmic & intermediate
membrane reticulum filaments
Plant Cell
PROTISTS
DOMAIN EUKARYA
EUKARYOTES
Mitochondrion Ribosomes
PROKARYOTES
Prokaryotic Cells
DOMAIN DOMAIN
BACTERIA ARCHAEA Prokaryotes have a simple cellular organization with
UNIVERSAL ANCESTOR no nucleus or other membrane-bound organelles
2. Artificial selection: Humans select traits in an Flagellum
organism’s offspring (e.g., pets, farm crops) Pili Cell wall
Domesticated Animals Ribosomes
DNA
Capsule Plasma
membrane
1
enerGy & life
Energy & Cells 5. Metabolism: Energy transfers within organisms are 2. Light-independent reactions (dark reactions):
1. Energy can be generally categorized relative to its passive based on sequences (metabolic pathways) of chemical Energized electrons are transferred to CO (reduction
2
or active state reactions involved in releasing (catabolic or exergonic) reactions) to form glucose (in the Calvin cycle)
A. Potential energy is stored for subsequent use to do or absorbing (anabolic or endergonic) free energy Cell Respiration
work 6. Enzymes: Biological catalysts; facilitate metabolic Highly energized electrons stored temporarily in glucose
B. Kinetic energy is in action or actively doing some chemical reactions by speeding up reaction rates and are removed (oxidation reactions) in a stepwise fashion
kind of work as a result of motion lowering heat requirements to maximize the energy captured at each step:
2. Energy can also be categorized based on specific types, Enzyme Kinetics 1. Glycolysis: Anaerobic process in cytoplasm in
including nuclear, magnetic, electrical, radiant, chemical, Enzyme & Enzyme-substrate Enzyme & product which glucose, a six-carbon compound, is oxidized to
substrate complex
and thermal (heat) two pyruvate molecules, which are both three-carbon
H H
A. Laws of natural physics dictate that when conversions Active O chains
between any specific kinds of energy occur, thermal site 2. Krebs cycle: Aerobic process that oxidizes pyruvate
energy will be involved, even if unintended Enzyme Enzyme Enzyme molecules to CO
2
B. For example, if radiant energy is converted into stored 3. Chemiosmotic phosphorylation: The energized
chemical energy (e.g., potential energy as a result of electrons released during the previous steps are used
7. Adenosine triphosphate (ATP): A high-energy
photosynthesis), heat will be produced to concentrate hydrogen ions in one area (of the cell
molecule; energy stored in ATP is released by
3. Laws of thermodynamics: The association between membrane in prokaryotes; of the mitochondrion in
breaking phosphate-to-phosphate bonds and
heat and all other energy forms is the foundation of the eukaryotes) to create a chemical gradient between
creating adenosine diphosphate (ADP) or adenosine
following natural laws: positively and negatively charged ions (like a battery);
monophosphate (AMP); ATP is recycled by adding
A. First law (conservation of energy): The total energy the potential energy resulting from this osmotic
back phosphate groups using energy from the Sun
in any closed system (i.e., energy cannot enter or exit) is gradient is used to resynthesize ATP from ADP and
Energy & ATP
always constant, but energy can change from one type AMP; after electrons have been used, they must be
to another; thus, energy cannot be created or destroyed transferred to O
B. Second law (increased entropy): The free or potential Energy 2
release Cell Respiration
energy to do work in a closed system decreases, whereas
entropy or disorder increases; thus, no energy transfer A P P P Chemical energy (high-energy electrons)
is 100% efficient in doing work (e.g., ATP production ATP
Chemical energy
during cell respiration will lose free energy in the form
of heat) A P P P
4. Earth is an open system Photosynthesis Glycolysis
A. Radiant energy from the Sun supplies organisms with Krebs Chemiosmotic
renewable energy to battle entropy and remain alive Sunlight or radiant energy is captured by chlorophyll Glucose Pacyirduvic cycle phosphorylation
and highly organized and carotenoid photopigments (found in cytoplasm in
B. Photosynthetic organisms (producers) convert radiant prokaryotes and chloroplasts in eukaryotes) in two main
Cytosol
energy directly into organic molecules (i.e., chemical steps:
energy), which are eaten by herbivores (primary 1. Light-dependent reactions (light reactions): The
consumers), which in turn are eaten by carnivores captured light energy is transferred to electrons that
(secondary consumers) come from H2O; O2 is a by-product ATP ATP ATP
cell transPort cell reProduction
Passive Transport Active Transport The Two Steps to Cell Reproduction
Passive transport relies on the thermal energy Active transport relies on the cell to provide the energy supply to 1. Mitosis: Division of nuclear material
of matter; the cell does not do work; there are move materials; there are three categories: 2. Cytokinesis: Division of remaining cellular
four categories: 1. Membrane pumps: ATP is required; a permease is used to move contents of the cytoplasm
1. Diffusion: Movement from an area of high a substance, usually in the opposite direction of diffusion The Cell Cycle
concentration to one of low concentration Membrane Pump Cells go through four stages during cell reproduction:
2. Facilitated diffusion: A permease, or 1. G: Active growth and metabolism
membrane enzyme, carries a substance 2. S:1 DNA synthesis and duplication
3. Osmosis: Diffusion across a semi- Glycoprotein 3. G: Synthesis of molecules in preparation for cell
permeable membrane Outside cell di2vision
4. Bulk flow: Mass movements of fluids A. Stages G, S, and G are collectively referred to as
affected by pressure and solutes interpha1se 2
Osmosis B. Interphase chromosomes are referred to
Pressure applied as chromatin, a diffuse, loosely scattered
to piston to resist arrangement of chromosomes
upward movement Phospholipid 4. Mitosis and cytokinesis: Mitotic chromosomes in
bilayer the mitosis-cytokinesis stage are highly condensed
Water plus solute and coiled and thus distinct
Pure water Cell Cycle
Selectively Inside cell Channel protein INTEGRPHASE
Molecule of solute pmeermmbearabnlee Cholesterol (Seco2nd
gap
Water molecules 2. EAn. Pdohcaygtoocsyist:o sMisa (tceerilal lesa atrien gb)r:o Sugohlitd isnto the cell via: ASE phase)Prophase M
3. BE.xP oPhcainygotooccysyittsoo:s siMsis a(tceerlila ldsr ainrPeki neinoxcgpy)et:lo lLseidisq furiodms theE xcoecllytosis Spreocdreutcotry ERTPNHI (SCyhnrretohpmelisScoisas topemhdaesse) GTeMlAopenhtaaapspehh aassee IT OSISC
1 Y
Net movement of water molecules CNytuocplleaussm CNytuocplleaussm CNytuocplleaussm Sveescircelteory INTE(RFpiPhrsHats Age)aSpE SISENIKOT
2
The Four Stages of Mitosis Crossing Over Female Reproductive Hormone Pathway
1. Prophase: Chromosomes condense and organize; Chiasmata Negative feedback Positive feedback
nuclear membrane and nucleoli disappear; spindle (majority of cycle) (days 12–14)
Hypothalamus
apparatus is assembled and attaches to centromeres
of duplicated chromosomes
GnRH
2. Metaphase: Spindles line up duplicated
chromosomes along equator of cell, one spindle to
Anterior pituitary
each half, or chromatid, of duplicated chromosome 2. Metaphase I: Homologues line up at equator
3. Anaphase: The centromere of each duplicated 3. Anaphase I: Homologues are separated into
LH & FSH
two groups, with each group having a mixture of
chromosome is separated, and paired chromatids
maternal and paternal chromosomes
are pulled apart 4. Telophase I: New haploid nuclei form for two new Ovary
4. Telophase: Chromosomes uncoil, nucleoli reappear,
daughter cells
cytokinesis occurs, and two genetically identical 5. Interkinesis: No replication of DNA occurs because Estrogen
daughter cells are produced each chromosome is still duplicated and consists &
Interphase Prophase Metaphase of two chromatids (although crossing over results Progesterone
Nuclear
Chromatin Condensing chromosomes in some chromatids with maternal and paternal
envelope
segments) Uterus
Meiosis II
Four daughter cells* 2. Ovarian cycle
Prophase II Metaphase II Anaphase II Telophase II A. Under the stimulation of FSH and LH, some (but
not all) follicles grow at different rates (during the
Cpaeinrstriole Nucleolus Bspeignidnlnei fnogrsm oaftion Spindle pole follicular phase), with the Graafian follicle maturing
the fastest; as the follicles grow, they also produce
Anaphase Telophase estrogen, with the Graafian follicle producing the
most
B. Estrogen has a negative feedback role on the brain
(both the hypothalamus and anterior pituitary) for
most of the monthly cycle, thereby keeping FSH and
LH levels relatively low; however, continually rising
*Four new cells are genetically unique and haploid
levels of estrogen from growing follicles trigger a
1. Prophase II: Chromosomes condense
Chromosomes Nuclear 2. Metaphase II: Chromosomes line up at equator positive feedback role that causes a temporary surge
decondensing envelope Cytokinesis in FSH and LH, with the latter hormone spiking the
reforming 3. Anaphase II: Chromatids of each chromosome are
most
separated
Interphase of Daughter Cells C. This surge in LH triggers ovulation, in which the
4. Telophase II: Each daughter cell from meiosis I
Graafian follicle bursts at the surface of the ovary and
will form two more cells for a total of four cells
releases a secondary oocyte covered in associated
Faunal & Floral Gametogenesis
follicular tissues (which will later become a barrier
1. In animals, meiosis occurs in germinal tissues and is through which sperm must pass to contact the
called spermatogenesis in males and oogenesis in oocyte)
Two new cells are genetically identical (i.e., clones) females; each results in gametes D. The remnants of the Graafian follicle now function
2. In plants, the process is similar, except that more as a corpus luteum (during the luteal phase), partly
orGanisMal mitotic divisions may follow meiosis to produce to prevent any additional follicles from developing
gametes and releasing potential eggs by combining estrogen
reProduction & Meiosis
Gametogenesis production with the additional hormone progesterone
Animal Plant (many birth control pills use this same hormonal
Sexual Processes Gametes Multicellular gametophyte strategy to prevent unwanted pregnancies)
1. mSeaxtueraial lr (egparmodetuecst)i forno min tvwoolv peas rethneta fl uosrigoann iosfm gsenetic n n n Mitosis n Mitosis E. Tfehrtei lciozarptiuosn l uantedu mim wplialln etavteionntu saullbys deiqsuinetnetglyra otec,c uunrless
2. To ensure the proper chromosomal numbers in the Meiosis Fertilization n n Spores n n 3. Uterine and menstrual cycle
zygote (fertilized egg), each gamete must have Gametes A. Estrogen and progesterone from the ovaries
Meiosis Fertilization
haploid, or half (N, or one set of chromosomes), of 2n stimulate the uterus to prepare for a potential
the original diploid (2N, or two sets of chromosomes) 2n Zygote 2n 2n embryo; specifically, the internal lining of the uterus
amount of DNA Mitosis Mitosis Zygote (endometrium) is partially shed at the beginning
3. Meiosis: The process by which the chromosome of each cycle (menstrual flow phase or “period”)
Multicellular organism Multicellular sporophyte
number is reduced by half, resulting in new genetic if there is no successful fertilization and subsequent
combinations in the gametes Reproductive Cycles & Hormones in implantation; increasing estrogen (from growing
The Two Stages of Meiosis Animals follicles) stimulates a thickening of the endometrium
Meiosis is preceded by interphase; many meiotic events Many animals, including humans, regulate the (proliferative phase)
are similar to those of mitosis; the following points note production of gametes and sexual behavior based on the B. After ovulation, increasing progesterone levels
the differences presence of and complex interplay between circulating additionally cause the endometrium to become highly
Meiosis I hormones that cycle based on monthly and seasonal vascularized and to secrete nutrients (secretory
Prophase I Metaphase I Anaphase I Telophase I rhythms phase) for embryo development; the disintegrating
Reproductive Control in the Human Female corpus luteum, and the concomitant drop in estrogen
1. Hormones and progesterone, causes vasoconstriction of
A. At puberty, the hypothalamus releases endometrial blood vessels, eventually leading to a
gonadotropin-releasing hormone (GnRH); this shedding of tissue and blood
stimulates the anterior pituitary to release follicle- C. If fertilization and implantation do occur during
stimulating hormone (FSH) and luteinizing the secretory phase and right after ovulation, the
hormone (LH) subsequent implanted embryo releases a hormone
Recombined chromosomes B. FSH and LH (but primarily FSH) trigger ovarian called human chorionic gonadotropin (HCG) into
Paired homologous chromosomes structures called follicles to grow and produce an the maternal circulation that helps maintain both the
1. Prophase I: Chromosomes condense and organize; oocyte (potential egg), as well as estrogen and corpus luteum and its secretion of the two primary
matched, or homologous, chromosomes (one progesterone steroid hormones, estrogen and progesterone
maternal and one paternal in each pair) are C. Estrogen and progesterone have major effects on D. The maintenance of the corpus luteum allows the
physically paired; segments of chromatids can cross the morphology and physiology of the uterus in endometrium to continue to develop and work with
over at breakage points called chiasmata within anticipation that ovulation and subsequent sexual the placenta of the embryo, while also preventing
each chromosome pair intercourse will result in a successful fertilization further follicle development and egg release
3
Ovarian, Uterine & Menstrual Cycle Fertilization & Development in Animals
The gametes produced during spermatogenesis Sperm Cell
Ovarianhistology Rfeoclrluicilteed Mfoaltluircilneg Ovulation Cdoergpeunse lruatteiounm at on1 d.p rAooo dsgpueecnreem so’ifssf asfpurern itcnhtgieonn u isse tdo d fuinridn agn fder ptielinzeattriaotne Acrosome (cNonutacilnesu esnzymes to help penetrate the ovum)
98.6°F an egg; sperm are much smaller than eggs
Body temperature Head Midpiece Tail
and include the following structures: (contains mitochondria (flagellum for movement)
96.8°F A. Head, which contains: for energy)
i. Acrosome: Contains enzymes necessary for fertilization; a high sperm count is required for the
Luteinizing hormone (LH)
Estradiol Progesterone minimum, collective amount of enzyme to break through physical barriers surrounding the potential
egg so that a single sperm can be involved in actual fertilization
nes Follicle-stimulating ii. Nucleus: Contains one complete set of DNA (i.e., haploid) from the male parent
mo hormone (FSH) B. Midpiece: Contains tightly packed mitochondria to make ATP for propelling sperm toward the egg
Hor n C. Tail: The flagellum that propels sperm
Follicular phase ulatio Luteal phase 2. eAxnte ergnga’ls s fturunccttuiorens i st htoro autgtrha cwt hanicdh r sepceerivme mspuesrtm p;e engegtrsa atere f moru scuhc lcaersgsefru tlh faenrt silpiezramtio ann dto i nocclcuudre: the following
v
Menstruation O Functional layer A. Corona radiata: Outer layer of attached follicular cells
of endometrium
B. Zona pellucida: Middle layer essential for sperm bonding and acrosomal activity
Endometrialhistology Basal layer 3. CFAe.. rVItniiilttieizalalli tnsitoean gm:e eSs mpbeebrfrmoar nea enc:do Pnertgaegcs etc nbotym i nsbp imenreamny nonmammalian anCimoraolnsa; sraimdiailtaar Efugngc tFioenr ttioli zzaotniao npellucida
i. In many animals, including humans,
chemical signals attract sperm to the egg Zona pellucida
1 2 3 4 5 6 7 8 910111213 141516171819202122232425262728 ii. Acrosome reactions prepare for a sperm’s
Menstrual Proliferative Ovulatory Secretory entry into the oocyte Secondary oocyte
phase phase phase phase
Days of Menstrual Cycle B. Final stages after contact by sperm
(Average values. Durations & values may differ between females & cycles.) i. Polyspermy prevention (i.e., allowing First polar body
Wikipedia & Wikimedia Commons • //commons.wikimedia.org/wiki/File:MenstrualCycle.png • creative commons cc-by-sa 3.0 license only one sperm to enter the oocyte)
E. After several months, the placenta takes over (a) Fast block: In some animals (e.g.,
directly for the production of estrogen and sea urchins), 1–3 seconds after sperm
progesterone for the duration of the pregnancy penetration, an electrical depolarization, or charge, occurs that blocks entry of additional sperm
i. Menopause: Human females typically ovulate into the egg
for a finite period, after which they also cease (b) Slow block: In many animals, entry of the first sperm triggers the formation of a barrier layer
having a menstrual cycle called the fertilization membrane directly outside the plasma membrane of the oocyte; the
ii. Estrous cycle: The endometrial lining thickens timing of completion of the slow block can vary from less than a minute to up to an hour (e.g.,
in all mammals; however, in most nonhuman mammals are typically slow)
and nonprimate animals, the endometrium is ii. The penetrating sperm’s head breaks off inside the oocyte, delivering one full set of chromosomes
not shed but rather reabsorbed if fertilization (i.e., haploid) from the male; the sperm nucleus is now called the male pronucleus
and implantation do not occur; behaviorally, iii. The penetrating sperm triggers the oocyte to complete the second meiotic division and produce
females are only receptive to a male for the actual ovum (and a nonfunctional polar body); at this point, the male pronucleus resides in the
reproduction during estrous (a.k.a. “heat”), cytoplasm of the ovum with the female pronucleus
which is the time associated with their uterus iv. Both pronuclei replicate their DNA and then fuse to complete fertilization to form the diploid
being ready for implanting an embryo; the zygote
estrous cycle may occur seasonally or yearly 4. Cleavage divisions: With the replicated DNA, the first cell divisions can now occur; in almost all animals
in some animals (e.g., bears) or much more there is an urgency to produce many cells rapidly; thus, the relatively large zygote cell is “cleaved” into
frequently in others (e.g., rats) numerous small cells
Reproductive Control in the Human Male 5. Embryonic stages: Most animals go through the following sequentially named stages:
1. At puberty the hypothalamus releases GnRH, which A. Morula: Solid ball of cells
stimulates the anterior pituitary to release FSH and B. Blastula: Hollow ball of cells
LH (called interstitial cell-stimulating hormone C. Gastrula: A tube grows into the blastula (a process called gastrulation) that will become the first
[ICSH] in males) digestive tract (archenteron) lined with endoderm; the outside is now the ectoderm; a middle layer
2. FSH stimulates spermatogenesis through the activity called the mesoderm will develop in most animals; at this point, the tissues and organs of the adult form
of Sertoli cells inside seminiferous tubules located in and begin to take shape (morphogenesis)
the testes Embryonic Stages
3. LH (ICSH) stimulates testosterone production
Morula Blastula Early gastrula Late gastrula
by Leydig cells, which are positioned between
neighboring seminiferous tubules
A. Human males can normally produce functional Archenteron
sperm throughout their entire lives, although men Endoderm
generally produce less testosterone and sperm as Ectoderm
they age, likely because of a variety of health- Blastocoel Blastopore
related issues
6. Embryo-parental relationships: Fertilized eggs vary in their physiological connection to and development
4. Negative feedback involving testosterone and inhibin
within the female parent
(produced by Sertoli cells) regulates overall hormone
A. Oviparity: Female lays fertilized eggs outside the body; the eggs continue to develop inside protective
levels
coverings (e.g., the hard shells of birds) using available nutrients directly available inside; embryos then
Male Reproductive Hormone Pathway
hatch while outside the female’s body
Negative feedback
Hypothalamus B. Ovoviviparity: Female produces eggs that are fertilized and surrounded with protective coverings using
available nutrients directly inside; embryos hatch from egg coverings while still inside the oviducts of
GnRH the female’s body; embryo eventually exits the female during birth
Negative feedback C. Viviparity: Female produces eggs that are fertilized and subsequently nourished inside the uterus of the
Anterior pituitary female’s body; embryo eventually exits the female during birth
i. Histotrophic viviparity: Embryos consume eggs or other embryos (e.g., intrauterine cannibalism in
LH FSH some shark species) for nutrients
ii. Hemotrophic viviparity: Embryos consume nutrients typically provided via a placental connection
Leydig cells Sertoli cells with the female parent’s blood supply
7. Human embryology: The blastula stage in humans is called the blastocyst, which is responsible for
Testosterone Spermatogenesis Inhibin
implanting (i.e., attaching) to the endometrium lining of the uterus; subsequently, the placenta will form to
Testis gain nutritional support from the mother’s blood supply
4
OrGanisMal reprOductiOn & MeiOsis (continued)
A. Early human embryos closely resemble other C. Expulsion of placenta (afterbirth): The membranous
vertebrates at similar developmental stages support system maintaining the fetus is eventually (typically Path of Embryo
B. After about 8–10 weeks, the embryo will more within 30 minutes of fetal expulsion) released from the Day 2 Two-celled embryo
closely resemble the form of the adult and is endometrium and passes through the cervix and vagina Morula Day 3–4 Day 1
called a fetus; gestation (i.e., development 9. Mammalian embryology: Classification of mammals is
First
inside the mother) is about 280 days or 9 based on developmental differences in embryos Uterus cleavage
months (from the time of the beginning of A. Monotremes (e.g., platypus and echidnas) lay eggs Day Oviduct
the cycle in which ovulation occurred) and is (i.e., oviparity) 5–6 Blastocyst Day 0
B. Marsupials (e.g., kangaroos, opossums, koalas) have
typically divided into three trimesters
8. Birth (parturition): Can be divided into three live births with embryonic nutrition provided through Day 8–9 Ovary Fertilization
a placenta (i.e., hemotrophic viviparity); however, the
major events in humans
embryo is born in an extremely underdeveloped state; Early stage of implantation Fimbria
A. Dilation of cervix: The inferior opening to
typically, the embryo subsequently crawls into a special
the uterus must dilate to accommodate the
pouch, or marsupium, on the mother where further
circumference of the baby’s head Fetal Development
embryonic development occurs while the embryo
B. Expulsion of fetus: Normally, the head will
nurses from mammary glands
pass through the cervix and vagina first;
C. Placentals (most mammals, including humans) have
breech births involving the opposite end live births after embryos develop using nutrients from
of the fetus are often problematic and may a more complex placenta than marsupials; additionally,
require surgical delivery via Caesarean placental mammal gestation periods are typically much
section longer than those of marsupials
Genetics & Mendel
1. Genetics: The study of traits and their v. Mendel’s first conclusions: Discrete factors Mendel Updated
inheritance (now known as genes) were responsible for the 1. Genes are found on chromosomes, and thus multiple
2. 19th-century biologists believed that traits traits, and these factors were paired, separated traits assort independently as long as they are located
blended; if blending occurred, things would (during meiosis), and recombined (during on different chromosomes; Mendel studied traits
become more similar, not different; Darwin and fertilization); alternate forms of factors or genes in peas that were each on separate chromosomes;
Wallace stated that variations or differences in exist called alleles; the F individuals had two genes on the same chromosome are linked and thus
1
offspring were necessary for natural selection to alleles, as their genotype (i.e., specific allele types will not normally assort independently
occur present for each gene) consisted of a dominant 2. Interactions between alleles
3. Gregor Mendel provided the most plausible and recessive allele (e.g., Rr, with R for round A. Complete dominance: One allele dominates
hypothesis for genetics, known as Mendelian and r for wrinkled seed); thus, the F individuals another allele
1
genetics, which is based on two laws developed were hybrids, as their phenotype (i.e., physical B. Incomplete dominance: Neither allele is
by using statistics to analyze results of crosses characteristics or traits) was similar to only one expressed fully
involving distinguishing traits of garden peas of the original parents (e.g., round seed) C. Codominance: Both alleles are expressed fully
A. Mendel’s first law, the law of segregation B. Mendel’s second law, the law of independent D. Multiple alleles: More than two alleles for a
of alternate factors, was developed using assortment, was developed using multiple-trait gene are found within a population
single-trait crosses crosses E. Epistasis: One gene alters the affect of another
i. Two true-breeding (i.e., those that i. Two true-breeding parents of different strains gene
consistently yield the same form when for two traits were crossed; the F individuals F. Polygenic inheritance: Many genes contribute
1
crossed with each other) parents (P1) with were then crossed, producing F2 individuals (see to a phenotype
different strains were crossed (e.g., round- figure) G. Pleiotropy: One gene can effect several
versus wrinkled-seed-producing plants) Independent Assortment phenotypes
ii. The offspring (F) from this cross all
1 Gray, short-haired Normal, long-haired H. Environmental influences: The genotype and
showed only one trait (e.g., a round seed),
P environment interact to form a phenotype
and this was called the dominant trait; thus, generation Parents Chromosomes & Sex Determination
the traits from the parents did not blend GG SS gg ss
1. In many animals, special chromosomes determine
iii. The F individuals were crossed with each Gametes
other t1o produce F individuals produced by GS gs sex and are called allosomes; the remaining
iv. ¾ of the F ind2ividuals expressed the P generation chromosomes are called autosomes
2 2. In humans, there are 44 autosomes and 2 sex
dominant trait, whereas ¼ expressed the
trait of the other P parent (e.g., a wrinkled geneFra1tion chromosomes: X and Y in males, X and X in
1 All GgSs females
seed) that had not been expressed in the
Sex Determination
F generation and was thus recessive (see Gametes form by segregation of alleles and individual
fi1gure) assortment
GS Gs gS gs
Segregation of Alternate Factors
Male Female
Gray female (GG) Normal male (gg) GG SS GG Ss Gg SS Gg Ss
GS Gray, Gray, Gray, Gray, F
P short short short short g2 Parents XY XX
generation GG Ss GG ss Gg Ss Gg ss e
Gs Gray, Gray, Gray, Gray, n
Gametes short long short long e
Pp rgoednuecreadti boyn G g All GgSs gS Gg SS Gg Ss gg SS gg Ss ra Gametes X Y X
Gray, Gray, Normal, Normal, t
short short short short i
F
genera1tion All Gg gs GGgra Sy,s GGrga sys, Ngogrm Sasl, Nogrgm ssal, on
Dominant G masks recessive g short long short long Zygotes XX XY
Gametes F phenotypes
Fp1r goednuecreadt iboyn G g 29 shorGt-rhaay,ired 3 lonGg-rhaayi,red Female Male
GG Gg F
2
G ge 3 Normal, 1 Normal, Sex-Linked Traits
n short-haired long-haired
e In humans, the Y chromosome contains the determinant
r
Gg gg a ii. Mendel concluded statistically that these results for maleness; the X contains many genes; if a male gets
All Gg g t occurred because alleles for one trait or gene did a recessive (or dominant) allele on the X chromosome
i
o not affect the inheritance of alleles for another from his mother, he will express the trait; therefore,
n
trait males are frequently afflicted with X-linked disorders
5
Molecular Genetics PoPulation Genetics
Genes, DNA & Nucleic Acids The Central Dogma Genes in Populations
1. Gene functions 1. Replication: DNA is copied from other DNA by vs. Individuals
A. To be preserved and transmitted unzipping the helix and pairing new nucleotides with 1. Populations evolve just as species do
B. To control various biological functions through the the proper bases (i.e., A with T and C with G) on each 2. Genotype: Genetic composition of an individual
production of proteins (i.e., large, complex sequences separated side of the original DNA 3. Gene pool: Genetic composition of a
of amino acids) and RNA 2. Transcription population of individuals (i.e., all alleles for
2. Gene structure is based on two nucleic acids: A. Messenger RNA (mRNA) is copied from DNA all genes in a population)
A. Deoxyribonucleic acid (DNA) by unzipping a portion of the DNA helix that 4. Evolution involves changes in gene pools
B. Ribonucleic acid (RNA) corresponds to a gene over time; to understand changes in gene pools
3. Nucleotides: The components of nucleic acids; made of B. Only one side of the DNA will be transcribed, and as populations evolve, an understanding of non-
three subunits: nucleotides with the proper bases (A with U and C evolving populations is necessary
Nucleotide
with G) will be sequenced to build pre-mRNA The Hardy-Weinberg Law
POhosPphOate– H NitroNgenousH basNe H C. raSeremeq suopevlneiccdee, dsa ntodog ft ehtehn reuercmleaoitniidnegs secgamlleendt s icnatlrleodn es xoanres 1. B(i.oet.h, g eanllee lpioc oflsre) qreumenacinie cso nasntda ngt fernoomty gpeince rraattiioons
O– O Sugar D. The mature mRNA leaves the nucleus to be to generation in sexually reproducing populations
CH if the following conditions of equilibrium exist:
2 N N translated by the ribosomes A. Mutations do not occur
RNA Synthesis & Transcription
B. There is no net movement of individuals out
H H HH N H G A G A G C A T C G TA C A A C. oAfl lo or fifnstpor ian gp opproudlautcioend have the same chances
A. Sugar (deoOxHyribose inH DNA; ribose in RNA) GC AT TA C T CTA GC C A U C G UTAT CGATGT T D. fnToahrte us rpuaorlv psiuevllaaeltc,i toiaonnn di s o mscoca utliransr)gg ei sth raatn cdhoamnc e(i .we.o, unlod
B. Phosphate DNA G G T A G C A not alter frequencies of alleles
C. Nitrogenous base (one of five possible bases) U RNA polymerase 2. Algebraic equivalent of the Hardy-Weinberg
i. In DNA, the nucleic acid of chromosomes, four C
nitrogenous bases are found: adenine (A), guanine mRNA A law: p2 + 2pq + q2 = 1, where:
(G), cytosine (C), and thymine (T) 3. Translation p = frequency of dominant allele
ii. RNA consists of similar bases, except uracil (U) A. Proteins are synthesized from mRNA by ribosomes q = frequency of recessive allele
replaces thymine (T) (which are composed of ribosomal RNA, or p2 = AA genotype
iii. DNA is a double helix molecule; that is, it is similar rRNA, and proteins), which read from a universal 2pq = Aa genotype
to a spiral staircase or twisted ladder, with the sides triplet code (i.e., codons) q2 = aa genotype
formed by repeating sugar-phosphate groups from B. The ribosomes instruct transfer RNAs (tRNAs) to
each nucleotide, and the horizontal portions (i.e., bring specific amino acids in the sequence dictated Example
steps) formed by hydrogen bonds involving A with by the mRNA, which in turn was built based on 1. If a group of six individuals has nine
T or C with G the sequence of nucleotides in the original gene dominant (A) alleles and three recessive (a)
iv. Hereditary information: Genes found along the portion of the DNA alleles, then p = 9/12 or 0.75 and q =
linear sequence of nucleotides in the DNA molecule Protein Synthesis 3/12 or 0.25; a total of 12 gametes will
DNA Double Helix be produced, 9 of which will have the
dominant allele and 3 of which will have
the recessive allele
2. Use the equation to predict the ratios of
the three possible genotypes as a result of
Amino acids tRNA
H fertilizations
H
H A. Frequency of AA genotypes is p2, or
5' G HH C 3' Trp (0.75)2 = 0.56
A HH T Polypeptide B. Frequency of Aa genotypes is 2pq, or
O OCH2 2(0.75)(0.25) = 0.38
–O P O O P O– C. Frequency of aa genotypes is q2, or (0.25)2
O O Phe = 0.06
CH2O A HH T CH2 RibostoRmNeA 3. aTlhleel efsr eaqruee nsctiilels tohfe dsoammien,a nbtu ta ntdh er escpeescsiifvice
–O P O O alleles have been redistributed
O P O–
O
H O Hardy-Weinberg &
CH2 C H G
O H CH2 Anticodon Natural Populations
––OOCOHPP2OOO G HHH C OOPOOCHO2– mRNA AUCGCGUAUAUAGGCCCG 12.. FtgTmheeheenwercee h fpHa(oinorfaioe rs,ldam scny hdsy- Wao) n ooegpfcieo ncspbut uiehrnl reia gsnat eil oln leanalewtseuv froarahlreluee qpt luipooienspnn uaceilridaqyeetu sin oialtcniinhfbsdyar n ituhgtmhueess;
O P O– by predicting that one or more of the four
O
CH2 G H C O Mutations conditions required are not met; that is, in
H natural populations:
O H CH2 A mutation is any random, permanent change in the A. Mutations occur
–O P O O PO O– DNA molecule; many mutations are harmful, some have B. Individuals leave and enter populations
O O no effect, and a few actually benefit the organism; nature C. Nonrandom mating and natural selection
CH2 T HH A selects those mutations that are beneficial or adaptive in occur
3' 5' organisms to help shape the course of evolution D. Small populations exist
Author: Randy Brooks, PhD U.S. $6.95 NOTE TO STUDENT: This guide is intended for informational purposes only. Due to its condensed format, this
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