Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIOL 2030 > Midterm #1 > Flashcards

Midterm #1 Flashcards

Modules 1-5

1
Q

Is a phenotype inherited?

A

NO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Telomere

A

stable ends of linear chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Centromere

A

constricted region of a chromosome where the kinetochore forms and spindle microtubules attach during cell division

holds sister chromatids together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Locus

A

position of a gene on a chromosome, or a particular location on a chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 4 types of chromosomes? (based on location of centromere)

A
  1. metacentric: centromere in centre
  2. submetacentric: centromere not quite in centre
  3. arocentric: centromere is very close to the end
  4. telocentric: centromere is at end of chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Autosomes vs sex chromosomes

A

autosomes: chromosomes that are the same in males and females

sex chromosomes: pair of chromosomes that differ between males and females

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Eukaryotic cell division: what’s shared with prokaryotes and what is only a eukaryote issue?

A

shared:
1. copy each chromosome
2. separate DNA into each daughter cell

only eukaryotes:
2. separate DNA into each daughter cell
- accommodate nuclear envelope
- ensure that exactly one copy of each linear DNA strand ends up in each daughter cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Kinetochore

A

complex of proteins that assembles at the centromere and serves as the site of microtubule attachment during cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Spindle microtubules

A

filaments responsible for moving chromosomes during cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Sister chromatids

A

2 linear chromatids that are connected by a centromere
- chromatids are genetically identical (unless crossing-over occurs during meiosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Briefly explain the stages of the cell cycle leading up to mitosis

A

G1: cell is smaller than normal after cytokinesis => cytoplasm reduced by 1/2
- cell grows to normal size
G0: growth, cell undergoes normal functioning
G1/S checkpoint: build machinery for duplicating DNA
S: DNA doubles
G2: new growth => get rid of machinery for genome synthesis, make machinery for mitosis
G2/M checkpoint: commit to shifting to mitosis

  • once past a checkpoint, cell cannot go back
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Are chromosomes always condensed/

A

NO; not until mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is it important that the nuclear envelope is still intact in prophase?

A

cell must wait for chromosomes to maximally condense for it to be safe for the microtubules to interact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Meiosis vs fertilization

A

meiosis: production of haploid (n) gametes)

fertilization: restoration of the diploid state (2n) in the next generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What’s the difference between metaphase and metaphase I?

A

in metaphase (mitosis) the chromosomes line up in a single line
in metaphase I the chromosomes line up in pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is meiosis I reductive?

A

2N => N

  • chromosomes line up in pairs and the centromeres do not separate in anaphase, leading to a reduction in chromosome count
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why is meiosis II equational?

A

N => N

chromosomes split like they do in mitosis, therefore no reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens in prophase I of meiosis?

A
  • pairing of homologous chromosomes
  • synapsis
  • tetrad (bivalent) structures
  • crossing over
  • visible chiasmata
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are two forms of genetic variation that can be linked to cell reproduction?

A
  1. new combinations of alleles for genes on the same chromosome
  2. different combinations of chromosomes within the haploid sets found in gametes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When does crossing over occur?

A

in prophase I of meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is crossing over?

A

the physical exchange of genetic material among sister chromatids
* only inner chromosomes undergo crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How/ when does independent assortment of chromosomes into gametes?

A

in metaphase I, the homologous pairs line up => this can be done in different ways, leading to variation

2^n = number of possible combinations (n = number of homologous gene pairs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the magic ratio? How do you get it?

A

9:3:3:1 => get it by crossing 2 doubly heterozygous individuals (YyRr x YyRr)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Dominance vs epistasis

A

both mask (hide) the expression of another allele

dominance: masks expression of an allele on the SAME locus

epistasis: masks expression of an allele on a DIFFERENT locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Epistatic vs hypostatic
epistatic gene: does the masking hypostatic gene: gets masked
26
What is the ratio for recessive epistasis?
9:3:4
27
What is the ratio for dominant epistasis?
12:3:1
28
What is the ratio for duplicate dominant epistasis?
15:1
29
What is the ratio for duplicate recessive epistasis?
9:7
30
Complementation
the expression of a wildtype phenotype in an individual carrying 2 mutant alleles => an indication that the mutant alleles are on different loci
31
Chromosomal sex determination systems
1. XX-XY system 2. XX-XO system 3. ZZ-ZW system 4. haplodiploidy
32
XX-XY system
females: XX (homogametic) males: XY (heterogametic) X egg + X sperm => female X egg + Y sperm => male ex: some insects, plants & reptiles, all mammals
33
XX-XO system
females: XX (homogametic) males: XO (heterogametic) X egg + X sperm => female X egg + O sperm => male ex: grasshoppers, other insects
34
ZZ-ZW system
females: ZW (heterogametic) males: ZZ (homogametic) Z egg + Z sperm => male W egg + Z sperm => female ex: birds, moths, some amphibians and fish
35
Haplodiploidy
no sex chromosomes system = number of chromosomes males: haploid (n) females: diploid (2n) ex: bees, wasps, ants
36
How do X and Y chromosomes pair during meiosis?
because of pseudoautosomal genes/ regions => these genes act like they are autosomal, allowing sex chromosomes to pair up
37
What leads to non-disjunction?
pairing and segregation of of X and Y can fail because they are not homologous
38
Non-disjunction in meiosis I vs meiosis II
meiosis I: no gametes will have normal haploid set (either n+1 or n-1)
39
Monoecious
condition of having both male and female reproductive structures in the same organism
40
Dioecious
species of organisms having either male or female reproductive structures
41
Mechanisms of sex determination
1. environmental 2. genetic 3. chromosomal (& haplodiploidy) *all systems involve genes
42
Genetic sex determination
sexual phenotype is determined by genes at one or more loci carried on autosomes - NO sex chromosomes in this system ex: some plants and protozoans
43
Environmental sex determination
sexual phenotype is determined in part, or in full, by environmental factors ex: different temperatures lead to male or female (or a mix) turtles
44
Chromosomal sex determination
autosomes vs sex chromosomes
45
Evolution of heterogametic sex (e.g., Y chromosome)
1. start as an autosomal pair 2. gain sex-determining genetic system(s) 3. crossing over (recombination) gets suppressed 4. chromosomes diverge between males and females (Y degeneration)
46
SRY
- encodes a protein that binds DNA (transcription factor) - function is to bend DNA => alters expression of other genes that determine testes development - "fundamental" (but not only) determinate of male phenotype - found in all mammals - genetic engineering: XX mice + SRY => male
47
Dosage compensation
mechanism that equalizes the amount of protein produced by X-linked genes between heterogametic and homogametic sexes mechanisms: 1. double the activity of X-linked genes in males (e.g., Drosophila) 2. half the activity of X-linked genes in female (e.g., C. elegans) 3. inactivate genes on one X chromosome in females (e.g., placental mammals)
48
Bar body
a mostly inactivated X chromosome in females - appears as dark stained "body" in nuclei of a cell - process of inactivation = lyonization
49
Lyonization
- occurs about 16 days after fertilization (500 to 1000 cell stage) - inactivation is random (diff. cell, diff. X chromosome) - females transcriptionally equivalent to single male X chromosome - yields functional hemizygosity (at the cellular level after 16 days) - 50:50 allelic expression: females are genetic mosaics (genes expressed differ from cell to cell) - X inactivation due to Xist gene
50
Anhydrotic ectodermal dysplasia
human X-linked trait characterized by several conditions including skin having no hair and no sweat glands - heterozygous women have irregular "patches" of affected skin
51
How are X-linked recessive genes transmitted?
1/2 sons are affected all daughters are unaffected, but 1/2 are carriers
52
Transmission of X-linked dominant genes (mother is heterozygous)
1/2 sons are affected 1/2 daughters are affected
53
How are X-linked dominant genes transmitted when the father has the gene but the mother is normal?
all sons are normal all daughters are affected
54
Transmission of Y-linked genes
only males are affected, trait does not skip generations ALL sons will get it
55
Genes on different chromosomes assort _________ of each other
independently
56
Linkage group
a collection of genes that do not assort independently into gametes because they are located on the same chromosome *not all genes in a linkage group are the same: strongly linked genes, weakly linked genes, genes very far apart assort independently
57
Inter-chromosomal recombination
assortment of alleles for genes on different chromosomes into novel (non-parental) combinations mechanism: random alignment of chromosome pairs (metaphase I) and segregation (anaphase I) in meiosis
58
Intra-chromosomal recombination
assortment of alleles for genes located on the same chromosome into novel combinations mechanism: exchange of DNA by crossing over (prophase I) in meiosis *genes must be far apart for this to occur
58
When are genes independent (un-linked)?
if they are located on different chromosomes, or located very far apart on the same chromosome
58
Complete linkage vs independence vs incomplete linkage
complete: only parental gamete types are produced; no crossing over; genes are VERY close independence: parental and recombinant gametes are produced with equal frequencies (50:50); crossing over occurs in every meiosis; genes must be very far apart incomplete: parental gametes are produced with greater frequency that recombinant gametes; crossing over occurs in some meioses; frequency of crossing over depends on distance
59
Genetic map
map of gene location on chromosomes obtained by using genetic recombination data 1% recombination = 1 map unit/ 1 centimorgan
60
Recombination frequency
percentage of recombinant progeny produced in a test cross max value is 50% = # of recomb. progeny/ total # of progeny
61
Coupling vs repulsion
*for heterozygous individuals coupling: dominant traits on same chromosomes repulsion: dominant traits on separate chromosomes
62
Coupling
NR phenotypes match parental chromosomes AND parental phenotypes
63
Repulsion
NR phenotypes match the parental chromosomes but NOT the parental phenotypes
64
Discontinuous (qualitative) trait
a trait having only a few, distinct, phenotypes; often with a simple relationship to genotype
65
Polygenic trait and types
a trait determined by the affects of alleles at many different loci 1. quantitative traits (continuous) 2. threshold traits (present or absent) 3. meristic traits (countable)
66
For a polygenic model, when do you not need to use the binomial formula?
when the probability = 0.5 if its does NOT = 0.5, you need to use the formula
67
QTL mapping
detecting the association between the inheritance of a trait and the inheritance of genetic markers if the alleles of the trait are close to the alleles of the marker, then most offspring that inherit a certain marker should also inherit the allele of the trait on that chromosome (i.e., contributing vs non-contributing allele)

BIOL 2030 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions