Biology/Zoology 101 UW-Madison (EXAM 2)
What are the components of the multistep model of cancer development?
(Usually > 1 mutation will yield cancer) Mutation 1: Cell starts to divide normally - Oncogene present - Mutated tumor suppressor (no apoptosis) Mutation 2: Cells ignore density-dependent inhibition (p27 protein prevents crowding) Mutation 3: Cells are no longer connected Mutation 4: Telomerase ON, cells immortal
What are three characteristics of sexual reproduction that attribute for variability?
*1) Random Alignment of chromosomes during metaphase I* (2^n combinations) -> n = haploid chromosome number ex: 2^23 different gametes *2) Crossing over* - Greater than 2^n combinations (Chiasma - site of crossover) *3) Fertilization* - Random sperm with random egg
Why is a pea a great model organism?
*1)* Easy to see traits *2)* Controlled matings *3)* Many offspring *4)* Short generation time
What is the purpose of the small intestines?
*Chemical digestion*: in *duodenum*, aided by accessory organs 1. pancreatic amylase - carbohydrates 2. pancreatic protease - proteins (trypsin, chymotrypsin) --> secreted as inactive precursors (trypsinogen, chymotrypsinogen) --> activated in SI 3. pancreatic nuclease - nucleic acids *Mechanical digestion*: - bile (from liver, stored in gall bladder) emulsifies fats ---> breakdown to smaller fat globules (Large SA for lipase to act and breakdown fat) *Absorption*: (molecules exchanged into circulation) - Occurs across small intestines within the folds - Within the folds are smaller folds called *villi* lined with epithelial cells and capillaries for absorption ---> lacteals between capillaries assist in transport through lymphatic system - Within the folds of villi are *microvilli* which provide more SA for absorption (face food)
How is cell division possible in eukaryotes versus prokaryotes?
*Eukaryotes* - Mitosis - > somatic cells - Meiosis -> gametes *Prokaryotes* - Binary fission
What are the four stages of Interphase and their functions?
*G0*: Resting stage - cell leaves stage when it receives signal to divide *G1*: Cell growth, transcription/translation, duplication of organelles, prepare for DNA replication *S*: DNA replication (only time) *G2*: More growth, transcription/translation, prepare to divide - centrosomes appear
What are the three types of epithelial cells within the gastric glands of the stomach?
*Mucous cells:* - Secrete protective coating (prevents gastric juice damage to stomach lining) *Parietal cells:* - Release H+ and Cl- into gastric gland lumen to ALLOW FOR PRODUCTION of HCl *Chief cells:* - Make pepsinogen (inactive form of pepsin) ----> HCl initially activates it to become pepsin [Positive feedback: amplifying a physiological change] --> pepsin activates more pepsinogen
Describe how simple animals can have direct exchange with their environment
- Thin, flat body shape - Very few cells - Live in moist environments
What is the principle of segregation?
Alleles separate from each other during meiosis
What is epigenetics?
Any process that alters gene activity without changing DNA sequence. Epigenetic phenomenon (changes that are reversible and can be passed to offspring): - Methylation -> adding -CH3 (turns genes off) - DNA packaging (loosely packed genes are expressed)
What is a byproduct of BRCA 2 mutations?
Damaged DNA, but still go through mitosis --> Increased risk for breast and ovarian cancer
What is the typical ratio of dihybrid crosses between two heterozygotes when the two genes are on different chromosomes?
9:3:3:1 (The middle 3s are considered recombinant)
What is the process that silences tumor suppressor genes?
Aberrant methylation - adding CH3 groups to mRNA (This is an epigenetic phenomenon -> no change in DNA sequence itself)
What are two ways that a proto-oncogene becomes an oncogene?
1) *Point mutation* --> misfolded protein 2) *Gene amplification/overexpression* --> normal growth - stimulating protein in excess (more copies of the same gene)
What are the four phases of Mitosis and what occurs in each?
1) *Prophase* (prophase and prometaphase) - nuclear envelope degrades - chromosomes condense - centrosomes migrate to opposite poles of cell --> mitotic spindle forms (centrosomes and MTs) - Kinetochore MTs: attach to both the kinetochores on each chromosome - Non-kinetochore MTs: don't attach to kinetochores 2) *Metaphase* - chromosomes line up on metaphase plate (imaginary line) 3) *Anaphase* - separates DNA - cohesin proteins degrade - Kinetochore MTs shorten --> sister chromatids separate and move to opposite poles of the cell - Non-kinetochore MTs get longer --> cell elongates (Each 1/2 of cell contains original number of chromosomes) 4) *Telophase/Cytokinesis* - nuclear envelope reforms in each 1/2 of cell - chromosomes decondense (unpack) - centrosomes and mitotic spindle disappear (cleavage furrow: band of microfilaments that assist in separation)
What are the different generations associated with genetics?
1) *True - breeding plants* (RR, rr) [P generation (P gen.)] 2) *First filial (F1) generation* --> one trait seen = dominant 3) *Second filial (F2) generation* --> two traits seen [3 purple, 1 white] <- *phenotypic ratio* (hidden trait in F1 generation = recessive)
What were the two theories of inheritance during Mendel's time?
1) Blending hypothesis (blue + yellow = green {hybrid}) - not true 2) Particulate hypothesis (blue +yellow = blue + yellow) - Mendel's model
What are the three functions of Mitosis?
1) Growth 2) Repair/ Replacement 3) Asexual Reproduction
What occurs for a Her2 proto-oncogene based on a normal signal and an amplification/overexpression signal?
1) Normal - Signal binds --> cell division, anti-apoptosis 2) Amplification/overexpression - Rise in gene copy number - Rise in mRNA transcriptions - Rise in number of cell surface receptors - Rise in rate of cell division (Herceptin: smart bomb type drug that mimics growth factors)
What are the components of the sexual life cycle of animals?
1. Gamete formation (meiosis) - diploid parent -> haploid gametes 2. Fertilization - union of egg and sperm -> diploid cell (2n = 46) 3. Growth (mitosis) and development
How does HPV act in order to affect a person's genome?
It integrates its DNA into the host's genome then the host transcribes/translates HPV genes. (PROBLEM: E6 protein binds to p53 which tells the cell to destroy the p53 protein)
What is the purpose of Leptin?
Leptin tells us when we are full -> appetite-suppressing hormone (affected by lack of sleep) Bigger fat cells -> more leptin secreted -> brain -> decreased food intake, increased metabolic rate Smaller fat cells -> less leptin secreted -> brain -> increased food intake, decreased metabolic rate
Does the inheritance of one trait influence the inheritance of other traits?
NOPE
What is the function of kinetochores?
Protein structure where microtubules attach during mitosis
What is the disease associated with trisomy of chromosome 21?
Down syndrome - genes on chromosome 21 correlate with phenotypes expressed
What is the theory of independent assortment?
Each pair of alleles segregates independently of each other pair of alleles during gamete formation.
T/F only eukaryotes carry out cellular respiration
False, ALL organisms carry out cellular respiration
T/F For every child, the likelihood of receiving a trait is based on the traits of past children
False, each child is an independent event
What are the pathways of fats and all other molecules from the jejunum and ilium (SI)?
Fats -> chylomicrons (lipoprotein complex) -> lacteals -> lymphatic system -> bloodstream All other molecules -> capillaries
What is the process that occurs when no oxygen is present for cellular respiration?
Fermentation 1) Lactic acid fermentation (muscle cells) (pyruvate -> lactic acid) - short, fast energy (2 ATP per glucose) 2) Alcohol fermentation (pyruvate -> ethanol)
What are some examples of intestinal adaptations?
For cellulose cell walls, a *cecum* is needed --> Anaerobic chamber with cellulose-digesting microbes *Also longer SI (more SA) for herbivores that requires the use of a cecum Ruminants - Rumin contains prokaryotes with cellulose-digesting enzymes -> regurgitation -> cud goes through chamber to animal's body for digestive enzymes
Describe sex-linked genes
There are a lot of genes on the x chromosome Y chromosome = "genetic wasteland" except for SRY ----> Gets male development going Males are hemizygous for sex-linked genes
What does it mean for a cell to be Aneuploid?
There is an abnormal number of chromosomes (not multiple of haploid number) [n+1 , n-1]
What are heterochromatin?
Tightly packed DNA (hidden traits)
T/F A dominant trait is NOT necessarily common within a population
True
T/F all the food we eat is used to make ATP (carbohydrates, proteins, and fats)
True
What are the names of proteins that inhibit tumors and their function?
Tumor suppressor proteins - Shut down cell division if conditions are not favorable - Detect and/or repair DNA damage - Promote apoptosis - Promote density-dependent inhibition
How many sister chromatids are in one chromosome?
Two
What is the function of NAD+ and FAD?
e- shuttles --> e-'s removed from food then transferred to shuttles NAD+ + 2e- + 2H+ --> NADH + H+ FAD + 2e- + 2H+ --> FADH2 * shuttle electrons to ETC
What is the molecule called that assists in the inhibition of telomerase?
RNA inhibition (interference) RNAi: Single-stranded nucleic acid complementary to normal mRNA molecule made by the cell (Antisense molecule: Complementary to telomerase mRNA which prevents telomerase creation)
What must the cells lining the stomach engage in due to constant damage by gastric juices
Rapid mitosis
What is the purpose of the large intestines?
Reabsorption of water --> Waste/undigested material becomes more solid --> Feces eliminated from the body (microbiome!)
Describe the maintenance of blood glucose homeostasis by hormones.
Stimulus: blood sugar level rises - Beta cells of pancreas release insulin into blood - Liver takes up glucose via facilitated diffusion and stores it as glycogen - Blood glucose level declines Stimulus: blood sugar level falls - Alpha cells of pancreas release glucagon into blood - Liver breaks down glycogen and releases glucose into blood - Blood glucose level rises
What activity is detected in almost all human tumors (leads to cell immortality)?
Telomerase (mice engineered to make telomerase in all cells -> cancer)
What does it mean for a zygote to be monosomic? trisomic?
monosomic: n-1 trisomic: n+1
Describe the respiratory surface of complex animals
small body surface relative to volume surface impermeable to gases --> need specialized exchange surfaces
What is a karyotype?
- Portrays pairs of chromosomes (within nuclear contents) - Humans are diploid (2n) (cells/organisms with paired chromosomes) - Gametes are haploid (1n, n) (no pairs of chromosomes)
What is another name for a centrosome?
Microtubule organizing center (MTOC)
What is the process that generates ATP?
ATP is produced by *phosphorylation* (ADP + P) 1) oxidative phosphorylation (ETC) 2) substrate level phosphorylation (glycolysis and krebs cycle)
What is cellular respiration and its formula?
Breakdown of organic fuels to make ATP C₆H₁₂O₆ + 6O₂ --> 6CO₂ + 6H₂O + ATPs (30-32)
According to recent groundbreaking research on Leptin, obese mice had a mutation in either...
Gene encoding leptin - no leptin made, appetite not suppressed Gene encoding leptin receptor (can't be treated with leptin injection) - leptin made, but targeting can't respond -> appetite not suppressed
What is a phenotype determined by?
Genotype
What is p53 and what occurs if mutated?
"The master watchman" responsible for regulating cell cycle activities. If mutated, damaged DNA/cells go through mitosis. --> colon, breast, lung, and other cancers
What is a genotypic and phenotypic ratio?
(Both are related to Mendel's Pea Plant experiments) *Genotypic* 1PP : 2Pp : 1pp *Phenotypic* 3 Purple: 1 White
What occurs during glycolysis?
*Overall:* one glucose molecule to two (3 carbon) pyruvate molecules *During production of pyruvates:* - Energy investment of 2ATPs to break down glucose (yields 2ADP + 2P) - 4ADP + P --> 4ATP (substrate level phosphorylation) [net gain of 2 ATP] - 2 NAD+ + e-'s + H+ --> 2 NADH *After production of pyruvates:* - pyruvates and 2 NADH move into mitochondrial matrix where pyruvate processing occurs ---> 2 pyruvates are converted to 2 acetyl CoA molecules ---> 2 CO2 and 2 NADH produced during the process per one glucose molecule
What are the events that occur within each stage of Meiosis?
*Prophase I* - chromosomes condense - nuclear envelope fragments - centrosomes migrate - *meiotic* spindle forms from centrosomes !! Synapsis occurs - pairing up homologous chromosomes (synaptonemal complex - protein lattice between homologous chromosomes) - cohesins: connect sister chromatids along length !! Crossing over occurs - exchange of genetic material between non-sister chromatids (meiosis I only) !! (Recombinant chromatids: sister chromatids that had cross over) *Metaphase I* - homologous pairs align on metaphase plate (random alignment = independent assortment) *Anaphase I* - kinetochore MTs shorten - synaptonemal complex degrades !! Homologous chromosomes separate -> move to opposite poles of cell !! Sister chromatids stay attached - non-kinetochore MTs lengthen thus the cell elongates *Telophase I/cytokinesis* - each 1/2 of cell has complete 1n set of replicated chromosomes !! each chromosome has two sister chromatids !! NO DNA replication occurs --> Both cells enter *Meiosis II* *Prophase II* - meiotic spindle reforms *Metaphase II* - chromosomes aligned on metaphase plate *Anaphase II* - sister chromatids separate and move to opposite poles *Telophase II/cytokinesis* - chromosomes decondense and nuclei reforms
What is required for gas exchange?
*Respiratory medium (air or water)* *Respiratory surface (exchange surface)* -> gases move by diffusion (high PO2, high PCO2 -> low PO2, low PCO2) *Circulation* - dissolved gases transported throughout body (O2 rich blood) *Membrane gas exchange* (high PO2, high PCO2 -> low PO2, low PCO2)
What is a chromosome?
- A structure carrying genes -- Genes and non-coding DNA
What is the amount of ATP produced by a single NADH and FADH2?
1 NADH -> ~2.5 ATP 1 FADH2 -> ~1.5 ATP per glucose molecule: 10 NADH -> 25 ATP 2 FADH2 -> 3 ATP
What is a human karyotype composed of?
22 pairs of autosomes and 1 pair of sex chromosomes (X & Y)
How would you describe the number of chromosomes in humans?
2n = 46 (diploid with 46 chromosomes) (gametes are n = 23)
What is the overall outcome of meiosis?
2n cell -> four 1n cells (daughter cells are not identical to parent cell or each other) ex: 2n = 6 cell -> four n = 3 cells
What is a pedigree?
A family tree of a genetic condition which can be used to track said trait. Recessive - not seen in parents but seen in offspring Dominant - seen in every generation
What is the outcome of Mitosis/Cytokinesis?
A parent cell is divided to create two identical daughter cells to the parent and each other (clones)
What is a good tool used to determine genotype and what does it entail?
A test cross is a good tool to determine genotype --> breed with homozygous recessive - If PP, all F2 offspring purple - If Pp, 1/2 F2 offspring purple and 1/2 white
Why is our form of gas exchange not entirely efficient?
Air flow is tidal: - gas exchange does not occur across entire respiratory surface - mixing of fresh and "dead" air - Inhalation (tidal volume) - Exhalation (residual volume) --> O2 depleted air is leftover in alveoli
What is diabetes and its different types?
Body does not produce or properly respond to insulin -> high blood pressure Type I diabetes (juvenile): - Autoimmune destruction of insulin-producing cells of pancreas -> no insulin made -> elevated blood sugar (Treated with blood sugar monitoring and insulin injections) Type II diabetes (adult) - Insulin made, cells can't respond -> Need abnormally high levels of insulin -> Pancreas can't meet demand -> Elevated blood sugar levels (Central obesity is a risk factor) (Type II has been seen increasing in teens/ children)
What is a requirement for true-breeding?
Both parents must by homozygous (BB and bb)
What happens if tumor suppressor proteins are mutated?
Cell cycle checkpoints are ignored. Damaged cells proliferate.
What is apoptosis?
Cell suicide pathway (kills off mutated/damaged cells)
What is the function of cohesins?
Connect sister chromatids along the length
What is the effect of certain poisons on cellular respiration?
Certain poisons interrupt critical events in cellular respiration --> impact proton gradient thus impeding ATP production
What are the two forms of digestion?
Chemical digestion: use hydrolytic enzymes Mechanical digestion: physical breakdown
What are hormones and how are they regulated?
Chemical messengers released into bloodstream that act on distant targeting cells [signal (hormone) -> receptor -> signal transduction pathway -> response] Many hormones are regulated by *negative feedback* --> control mechanism that reduces a stimulus and allows an animal to maintain homeostasis --> keep hormone levels within a particular, appropriate physiological range
What is digested food in the stomach called?
Chyme
What is oxidative phosphorylation?
Combination of electron transport and chemiosmosis (coupling the formation of a proton gradient with ATP production)
What is a good tip for determining the number of chromosomes?
Count the centromeres
What does it mean to be a bulk feeder?
East relatively large pieces of food
What are the functions of proto-oncogenes?
Encode signals, receptors, signaling molecules, and control proteins
Describe a tracheal system as a respiratory surface
Extensively branched system of internal tubules (spiricles) - Adapted for gas exchange in terrestrial environments (insects, centipede, millipede, some spiders) - Brings outside environment close enough to nearly every cell to diffuse --> no direct contact with blood vessels needed
Describe the process of x - inactivation
Extreme DNA packaging - Occurs early in development --> One chromosome in each cell becomes condensed (random) (Barr bodies) ex: mosaic fur pattern in female calico cats (more common than in males)
What are the functions of BRCA 1 and BRCA 2 genes?
Helps repair DNA at G2 - Recognizes breaks in chromosomes - Recruits repair enzymes
What is the process of radiation therapy?
High energy particles damage DNA --> Cells destroyed/injured
Describe lungs as a respiratory surface
Infoldings of throat (vertebrates) - Adapted for gas exchange in terrestrial environments (trachea -> bronchi -> bronchioles -> alveoli) - Film of liquid contains *surfactant* -> keep alveoli open and moist - Breathing ventilates the lungs -> negative pressure breathing: pull air into lungs (P down, volume up) (diaphragm contracts)
What is the process of traditional chemotherapy?
Injection of chemicals into blood stream to kill dividing cells --> Some prevent mitosis - Taxol: prevents kinetochore MTs from shortening --> Some stop DNA replication
What are euchromatin?
Loosely packed DNA (expressed traits)
What is the effect of uncouplers?
Make IMM "leaky" so no proton gradient build up
How do the two types of digestion occur in the mouth (oral cavity)?
Mouth: mechanical digestion Saliva: chemical digestion - salivary amylase: important hydrolytic enzyme - mucus and antibacterial agents are also important
Why is gas exchange difficult in water?
Much less O2 than air Water is more dense and viscous than air O2 diffuses much slower than in air
How does the exchange of materials occur?
Occurs as substances dissolved in an aqueous solution move across the plasma membrane of each cell --> cells with entire SA in contact with water
What is sexual reproduction?
Offspring are not identical to parents
What is asexual reproduction?
Offspring identical to parent (clone) - Binary fission, mitosis/cytokinesis
What are proto-oncogenes called after they mutate?
Oncogenes (cancer-causing genes)
What does it mean to be autosomal dominant?
Only one mutated allele needed Having some abnormal protein --> trait ex: In an autosomal dominant disease, if you inherit the abnormal gene from only one parent, you can get the disease.
Describe gills as a respiratory surface
Out foldings from body - adapted for gas exchange in aquatic environments Gills have huge SA directly in contact with water - *ventilation mechanisms* (water through mouth, throat muscles) - *one-way flow* of respiratory medium (in mouth, out gills) - *counter current exchanger* (maximum amount of O2 from water --> direction of water flow opposite direction of blood flow (PO2 in water always higher than PO2 in blood) -> gradient for diffusion all along capillary bed
What is produced during the citric acid cycle (krebs cycle)?
Per acetyl CoA: - 3 NADH - 1 FADH2 - 1 ATP (substrate level phosphorylation) - 2 CO2
Describe the Electron Transport Chain and the processes within it
Series of molecules and molecular complexes that can accept and donate electrons. (electrons are pulled to greater affinity(left to right)) Electrons from NADH move down the ETC ---> complexes I, III, and IV are H+ pumps (active transport of H+ from matrix to intermembrane space) ---> FADH2 donates electrons to protein complex II which does not affect proton gradient Establish a proton gradient - energy to pump H+ across gradient comes from movement of electrons down ETC H+'s move through ATP synthase --> production of ATP *ALL THIS IS POSSIBLE BECAUSE OXYGEN IS PRESENT* Oxygen is the final electron acceptor 1/2 O2 + 2 H+ + 2e- --> H2O
Describe complex animals
Specialized exchange surfaces (specific organs and organ systems) - internal or external - large SA ---> folds and branches - connected to circulatory system - thin ---> layer of epithelial cells - composed of living cells - moist interstitial fluid
What is the purpose of the stomach?
Storage - gastric folds present Mechanical digestion - peristalsis/churning Chemical digestion - gastric juice -> digests meat (protein) HCl (pH = 2): kills bacteria, denatures proteins, activates protease *pepsin: protease (chemically digests proteins)
What is co-dominance?
The F1 generation heterozygote phenotype consists of distinct phenotypes of both parents ("patches", no blending) Genes may have >2 alleles (ex: ABO blood system) (A and B are codominant (AB blood)) (A and B are separately dominant to O)
What is incomplete dominance?
The F1 generation heterozygote phenotype is considered intermediate (blend) F2 generation: phenotype ratio = genotype ratio --> 1:2:1
When chyme goes from the stomach to the small intestines (duodenum), what is the role of the pancreas?
The pancreas releases bicarbonate in order to neutralize acid chyme.
What happens to chromosomes at the start of Mitosis?
They become compact (condense)
What are some common features for respiratory surfaces?
Thin, large SA, moist, contact with circulatory system (usually), and composed of living cells. - body surface gas exchange for earthworm (single cell body surface with capillaries underneath)
What is nondisjunction?
When homologous chromosomes or sister chromatids don't separate (Go to one side instead 50:50 distributions)
When do the components of the gastric juice activate in the stomach?
When they are released into the lumen of the stomach (gastric juice not released until food arrives in stomach).