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BIO 111 Exam 1
| Question | Answer |
|---|---|
| Define ploidy | The number of copies of each type of chromosome a particular cell has |
| Differentiate between haploid, diploid, and triploid | haploid - one individual chromosome of each type diploid- pair of chromosomes triploid - 3 of each type (*only in plants) |
| Define aneuploidy | Not having the true/correct number of chromosomes |
| What are the three universal requirements for cell division? | Replication of genetic material Accurate segregation of genetic material Division of the cytoplasm |
| How do bacteria divide? | Binary fission |
| Describe binary fission | Replication and segregation are coupled: Replication begins at origin of replication of DNA and happens bidirectionally around until it reaches the terminus Segregation is an active process which requires the FtsZ protein to form a septum for segreation |
| How is FtsZ regulated and in what organisms is this done? | Cyanobacteria; if light is present, KaiA,B, or C are needed to develop FtsZ |
| Define karyotype | The number of chromosomes an organism has |
| Each chromatid has is own individual __________. | centromere |
| Differentiate between centromere, kinetochore, and telomeres | Centromeres hold sister chromatids together and are made of repeated DNA Kinetochores are proteins at the centromere that attach to microtubles Telomeres cap chromosomes for protection |
| What are three problems the cell must solve regarding replication? | Chromosomes must be compacted Must keep chromatids attached because chromosomes are not labelled Release of attachment is irreversible |
| How are chromosomes compacted in the cell? | DNA wraps around a histome (4 protein charged); 1 histome forms two tetrameres; many histomes form nucleosome; many nucleosomes form loops called solenoids; solenoids coil and wrap around protein scaffolds |
| What are the 5 phases of the eukaryotic cell cycle? | 1. G1; 2. G2; 3.S; 4.Mitosis; 5.Cytokinesis |
| How is the cell cycle controlled? | Phosphorylation events: Regulatory protein cyclins enter the cell during mitosis and allow cyclin-dependent kinase enzymes to phosphorolate transcription factors necessary for gene expression |
| When are the 3 checkpoints in the cell cycle? | The beginning between G1/S boundary G2/M transition Prior to anaphase (spindle checkpoint) |
| What is the overall function of mitosis? | To segregate chromosomes |
| Microtubule dynamics? | |
| What holds sister chromatids together? | Cohesion proteins |
| Describe prophase (4) | 1. Chromosomes condense 2. Nuclear membrane breaks down 3. Spindles form 4. Chromosomes attach to spindle at kinetochore |
| Describe metaphase (3) | 1. Chromosomes move to metaphase plate 2. Centromeres attached to opposite poles via microtubles 3. Chromosomes are under tension |
| Anaphase (3) | 1.Centromeres separate 2. Each chromatid is now a single chromosome/ chromosome number doubles but DNA amount remains 3. Chromosomes pulled to opposite poles |
| Telophase (2) | 1. Chromosomes decondense 2. Nuclear membrane forms |
| What are the the two movements in anaphase | A. chromosomes move to poles B. poles move apart |
| How are cohesions degraded to separate centromeres in anaphase? | By protease; signal comes from anaphase promotion complex at spindle checkpoint |
| Differentiate cytokinesis in animals and plant | Animals - use a contractile ring: actin/myosin microfilaments pinch the cell producing a cleavage furrow Plants - Cell plate forms between cells |
| What is the overall purpose of Meiosis? | Segregation of cells to produce haploid gametes |
| Why aren't sister chromatids identical in meiosis | Recombination/ Crossing-over |
| At the end of meiosis I are cells diploid or haploid? | Haploid |
| Define homolog | Members of a chromosome pair |
| What are the 3 main differences between meiosis I and mitosis? | 1. Homologues pair in PI 2. Homologous pair aligns at MI 3. Homologoues separate in AI |
| How do homologes pair in PI? | Held together by proteins(chiasmata) forming the synaptonomal complex |
| When can crossing over be detected? | When new combinations of alleles are generated in a chromosomes |
| How does MII differ from Mitosis? | Results in 4 haploid cells; No other differences |
| What happens between MI & MII | Interkinesis... chromosomes unwind; NO replication |
| Define autosomal | Genes on nonsex chromosoomes |
| When can crossover occur? | PI |
| What rearranges chromosomes? | Crossing over |
| Describe prokaryotic cells (in terms of cellular division characteristics) | DNA is spread through out the cytoplasm in 1 circular chromosome |
| In anaphase of mitosis chromosome number _______. | doubles |
| * Review number meiosis chart * | |
| Can crossing over occur between sister chromatids | NO |
| Define gene | Portion of DNA with info. necessary to a specific trait |
| Define locus | location of a gene on a chromosome |
| Define allele | Different forms of a gene |
| Define genotype | Alleles carried by one individual |
| Define phenotype | Appearance of individual/ how genes get expressed |
| Define true-breeding | Always showing a better trait |
| What is the principle of segregation? (2) | Maternal and paternal alleles segregate during gamete formation; Homologs disjoin during anaphase I so alleles separate then as well |
| In a monohybrid cross, the outcomes are... | equally likely |
| Define dihybrid cross | 2 factor cross |
| In a dihybrid cross, many combinations occur if ...? | 2 loci are independent from each other |
| What's the principle of independent assortment? | Alleles for each locus are segregated independently because chromosomes segregate independently during meiosis |
| How do you predict the offspring of independently assorted crosses? | Product Rule: product of all of the individual probabilities |
| What's the F2 offspring genotypic ratio in a dihybrid cross | 9:3:3:1 |
| n loci --> ___ genotypes; ____ phenotypes; ___ gamtetes | 2^n; 3^n; 2^n |
| How do you determine whether an organism is Rr or RR? | Test cross: R___ x rr |
| What is incomplete dominance? | Gene expression depends on enzyme activity (i.e. red + white flowers) |
| What is codominance? | Heterozygote shows both phenotypes (i.e. blood type.. AB) |
| In labrador's what do the B and E alleles do? | B affects color ( B=black, b=brown); E affects expression of color (regulatory; E=expressed, e=not expressed: yellow) |
| Define epistasis | One gene regulating the expression of another (i.e. labrador's) |
| In Morgan/Fly genetics, how are dominant, recessive, and wild type alleles represented | Dominant have upper case; recessive have upper case; wile type have +; alleles separate by a / |
| What is sex linkage | Genes for a given trait are located on a sex chromosome |
| Differentiate between hetero- and homogametic sex chromosomes | Hetero-2 kinds of sex chromosomes & will be hemizygous (human males) Homo- 2 copies of one kind of sex chromosome |
| Define hemizygous | Only one copy of an allele in a diploid organism |
| 2 % of the human genome is ________; the remaining 98 % is used for _________. | Coding; regulatory functions |
| What's the difference between complete and incomplete sex linkage | Incomplete: equal number of parental and recombinant offspring Complete: Only parental offspring |
| Fl (a+b/ab+) if two alleles are _____. F1 (a+/a b/b+) if two alleles are ____. | linked/ on same chromosome unlinked/ on separate chromosome |
| In ___________ you will see more parental genotypes than recombinant in the F1 generation | Linkage |
| What allows us to map genes? | Recombination |
| Relationship between genetic mapping and recompination | 1 map unit = 1% recombination = 1cM |
| How to calculate map distances | 1. Are genes linked(excess parental)? 2. Calculate recombination frequency(recombinated/total). 3. Convert to % for map distance |
| As distance on chromosomes increases, recombination frequency does what? | increases |
| An odd number of cross-overs shows ________ offspring; An even number of cross-overs shows __________ offspring. | Recombinant; parental(can't tell) |
| What's the maximum recombination frequency? | 0.5/50% |
| __________________ can be used to put genes in order because the gene in the middle allows us to see recombination events on the other side | 3-point crosses |
| Define nondisjunction | The failure of sister chromosomes to separate properly during meiosis |
| What does it mean for an allele to not independently assort? | The alleles can't separate and there is no diversity in combinations |
| The fact that 'R' separates from 'r' in gamete formation is an example of what? | The law of segregation |
| Does independent assortment occur in epistasis? | Yes; but the genes do not behave independently/ traits are not independently expressed |
| A human sperm cell would be described as (a)haploid (b)2n=46 (c)1n=23 | A/C |
| Do cyclins add phosphate groups to other molecules? | No! They regulate |
| In incomplete dominance what are the F1 genotypic and phenotypic ratios | 1:2:1 |
| If codominance were a factor, what would the offspring of a blue crossed with a red flower look like? | Blue and red spotted |
| What are the symbols in a pedigree chart for male, female, cross, affected, unaffected | Male = square; female= circle; cross=line between male and female; affected=colored; unaffected=empty |
| What are the four hypothesis a pedigree analysis tests? | Autosomal recessive; autosomal dominant; sex-linked recessive; sex-linked dominant |
Created by:
jkmccord11
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