Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MED-103 Biology I (2024-25) > Topic 11: meiosis > Flashcards

Topic 11: meiosis Flashcards

1
Q

Compare sexual/asexual reproduction

A

ASEXUAL:
- Single individual passes genes > offspring = without fusion of gametes
- Offspring are genetically identical clones of parents
SEXUAL:
- 2 parent to create offspring = combination of genes inherited from both parents

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

What is the role of meiosis in sexual reproduction?

A
  • Reproduction is via fertilization of gametes
  • Gametes produced by meiosis
  • Fertilized egg = zygote
  • Zygote produces somatic cells via mitosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define meiosis

A
  • Cell division producing gametes
  • Reduction of chromosomes half = n = 23
  • Produces haploids from diploids
  • After fertilization = 2n
  • Produces haploids from diploids
  • 2 sets of cell division
  • 4 daughter cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define karyotype

A
  • Ordered display of pairs of chromosomes in a cell
  • Each somatic cell = 44 autosomes = 22 pairs
    • 2 sex chromosomes XX/XY = 46 in total
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define autosomes

A
  • Chromosomes that don’t determine sex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define homologous chromosomes

A
  • 2 chromosomes in each pair during meiosis
  • 1 paternal 1 maternal
  • Same length + shape + carry genes controlling the same inherited characteristic
  • Same gene = different alleles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define gene locus

A
  • Location of a particular gene on a chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the difference between animal sexual life cycle + other organisms

A

ANIMAL:
- Gametes = only haploid cells + only produced via meiosis + don’t undergo further division
- Only diploid cells divide by mitosis
PLANTS/FUNGI/PROTISTS
- Both haploid /diploid cells divide by mitosis

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

Describe the difference between meiosis I + meiosis II

A
  • Meiosis I = separates homologous chromosomes = 2 haploid replicated chromosomes
  • Meiosis II = separate sister chromoatids = 4 haploids unreplicated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe meiosis I

A
  • Interphase =chromosomes duplicate = sister chromatids + centrosomes duplicate
  • 4 phases:
    > Prophase I
    > Metaphase I
    > Anaphase I
    > Telophase I/cytokinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe prophase I

A
  • 90% time of meiosis
  • Chromosomes start to condense
  • Synapsis = pairing homologous chromosomes = each pair forms tetrad = synaptonemal complex
  • Genetic recombination = crossing over = exchange of DNA segments between non-sister chromatids in the homologous chromosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe metaphase I

A
  • Tetrads line up at metaphase plate
  • Microtubules from poles attached > kinetochore of each chromosome in tetrad
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe anaphase I

A
  • Homologous pair separate = move to opposite poles
  • Sister chromatids = stay attached at centromere
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe telophase I + cytokinesis

A

TELOPHASE:
- Each half of cell has haploid set = 2 sister chromatids
- Cleavage furrow forms = division = 2 haploid daughter cells

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

Describe meiosis II

A
  • Similar to mitosis
  • 4 phases also:
    > Prophase II
    > Metaphase II
    > Anaphase II
    > Telophase II + cytokinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe prophase II

A
  • Spindle apparatus forms
  • Chromosomes move towards metaphase plates
17
Q

Describe metaphase II

A
  • Sister chromatids arranged at metaphase plate
  • If crossing over occurred in meiosis I = sister chromatids may not be genetically identical
  • Microtubules attach to kinetochores
18
Q

Describe anaphase II

A
  • Sister chromatids move towards opposite poles = separate
19
Q

Describe telophase II + cytokinesis

A

TELOPHASE
- Nuclei reforms + chromosomes decondense
CYTOKINESIS
- Division of cytoplasm
- 4 daughter cells = genetically distinct

20
Q

3 unique events in meiosis

A

1) Synapsis + crossing over
2) Metaphase I = alignment of homologous chromosome pairs instead of individual
3) Anaphase I = separation of homologous chromosomes instead of sister chromatids

21
Q

Compare/contrast mitosis/meiosis

A

DNA REPLICATION
- Mitosis + meiosis = occurs in interphase before it begins
NUMBER OF DIVISIONS
- Mitosis = 1 including all phases
- Meiosis = 2 all phases done twice
SYNAPSIS OF HOMOLOGOUS CHROMOSOMES
- Meiosis = during prophase I
NUMBER OF DAUGHTER CELLS
- Mitosis = 2 diploids = 2n = genetically identical
- Meiosis = 4 haploids = n = genetically variability

22
Q

4 factors causing genetic variation

A

1) Crossing over = genetic recombination
2) Independent assortment of chromosomes = 2^23 combinations of homologous chromosomes = 8 million gametes
3) Random fertilization = 64 trillion possible offspring
4) Mutations = create different versions of genes

23
Q

Describe independent assortment

A
  • Homologous pairs align randomly in metaphase I
24
Q

Explain the evolutionary significance of genetic variation

A
  • Sexual reproduction = genetic variation = via mutations
  • Natural selection = genetic variation that’s favored

MED-103 Biology I (2024-25) (13 decks)

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