Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > Genetics HL > Flashcards

Genetics HL Flashcards

(45 cards)

Start Studying
1
Q

What is S phase of Interphase

A

DNA replication that will result in two chromosomes that contain two identical DNA strands

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

What is S phase of Interphase

A

DNA replication that will result in two chromosomes that contain two identical DNA strands called sister chromatids. Held together by a centromere

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

What happens to sister chromatids in meiosis II

A

Become independent chromosomes each made of a single DNA strand

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

Meiosis Phases

A

Two divisions following the same pattern
Prophase, Metaphase, Anaphase, Telophase

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

Meiosis I

A

reduction division (diploid → haploid) where chromosomes are separated
P-1: Chromosomes condense and the nuclear membrane breaks down. Homologous chromosomes form bivalent where they cross over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Prophase I

A

Chromosomes condense and the nuclear membrane breaks down. Homologous chromosomes form bivalent where they cross over

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

Metaphase I

A

Spindle fibres from opposing centrosomes connect to bivalent at the centromeres and align them along the middle of the cell

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

Anaphase I

A

Spindle fibres contract and split at the bivalent and the homologous chromosomes move to opposite ends of cell

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

Telophase I

A

Chromosomes condense and the nuclear membrane reforms. cell divides (cytokinesis) to form two haploid daughter cells

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

Meiosis II

A

Separated the sister chromatids and are not identical during crossing over in prophase I

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

Prophase II

A

Chromosomes condense and the nuclear membrane breaks down. Centrosomes move to opposite poles (perpendicular to before)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Metaphase II

A

Spindle fibres from opposing centrosomes attach to chromosomes and align along equator

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

Anaphase II

A

spindle contract and separate the sister chromatids. Now chromatids called chromosomes move to opposite poles

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

Telophase II

A

Chromosomes decondense, nuclear membrane reforms, cells divide (cytokinesis) to form four haploid daughter cells

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

What is the final product of meiosis

A

four genetically destinct haploid daughter cells

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

independent assortment

A

how pairs of alleles separate independently from one another during gamete formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

the inheritance of one trait is dependent to the inheritance of any other trait. True or false

A

False

it is independent

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

How does Independent assortment come about

A

Random orientation of pairs of homologous chromosomes in meiosis I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When will independent assortment not occur

Study These Flashcards
A

if two genes are located on the same chromosome

20
Q

Synapsis

Study These Flashcards
A

How homologous chromosomes become connected in prophase I. Connected by a protein-RNA

21
Q

bivalent

Study These Flashcards
A

bi = two chromosomes

22
Q

autosomes always undergo synapsis during meiosis, sex chromosomes often remain unpaired. True or False

23
Q

Chiasmata

Study These Flashcards
A

hold the homologous chromosomes together as a bivalent until anaphase I

24
Q

How do chiasmata form

Study These Flashcards
A
  1. non-sister chromatids break and recombine with their homologous partner (crossing over)
  2. non-sister chromatids remain physically connected at these points of exchange

Chiasmata formation between non-sister chromatids can result in the exchange of alleles (recombination)

25
Crossing over cannot increase genetic diversity. True or false
False It can
26
what does a large gene pool suggest
High amounts of genetic diversity increase the chances of biological fitness
27
5 Mechanisms of Change
- Mutation - Gene Flow - Sexual reproduction - Genetic Drift - Natural Selection
28
Population Bottlenecks
When a population side reduces by more than 50%. The surviving population has less genetic variability than before and will be subject to a higher level of genetic drift. As the newly developing gene pool will be divergent to the original
29
Founder Effect
when a small group breaks away from a larger population to colonise a new territory. It does not have the same level of diversity and can result in more genetic drift. And as they increase in size the gene pool will not represent the original gene pool
30
What are the three types of selection
Stabilising Selection Directional Selection Disruptive Selection
31
Stabilising Selection
intermediate phenotype is favoured at the expense of both phenotypic extremes - Remove extreme phenotypes and happens when environmental conditions are stable and competition is low
32
Directional Selection
phenotypic extreme is selected at the cost of the other phenotypic extreme - Clear shift in one direction the beneficial extreme - Happens in response to gradual changes in environmental condition
33
Disruptive Selection
both phenotypic extremes are favoured at the expense of the intermediate phenotypic ranges - phenotypic distribution to deviate from the centre and results in a bimodal spread - occurs when fluctuating environmental conditions - Continued separation of phenotypic variants may eventually split the population into two distinct sub-populations
34
Types of reproductive isolation
- Prezygotic isolation – occurs before fertilisation can occur (no offspring are produced) - Postzygotic isolation – occurs after fertilisation (offspring are either not viable or infertile)
35
Temporal Isolation
two populations differ in their periods of activity or reproductive cycles
36
Behavioural Isolation
two populations exhibit different specific courtship patterns
37
Geographic Isolation
two populations occupy different habitats
38
Speciation
the evolutionary process that results in the formation of a new species from a pre-existing species. And occur when isolating mechanisms prevent two breeding organisms from producing fertile, viable offspring
39
Two mechanisms can occur during speciation
- Allopatric speciation (geographical isolation) - Sympatric speciation (reproductive isolation)
40
Allopatric Speciation
when a geographical barrier physically isolates populations of an ancestral species - two populations begin to evolve separately as a result of cumulative mutation, genetic drift and natural selection
41
Sympatric Speciation
divergence of species within the same geographical location (no physical barrier) - Results of reproductive isolation of two populations as a result of genetic abnormalities
42
Polyploidy Offspring
viable and fertile but cannot interbreed with the original parent population
43
what do fertile polyploid offspring require
two polyploid parents as reproduction with the original parent results I'm offspring with uneven amount of chromosome sets
44
Phyletic Gradualism
continuous change
45
Punctuated Equilibrium
Rapid change then stable

Biology (12 decks)

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