Topic 1 Reproduction,1.1,Mitosis&Meiosis Flashcards
What is the purpose of mitosis in the process of gametogenesis?
To expand the PGC population
What comes before mitosis and meiosis?
interphase:
G1 (normal growth), S (DNA rep), G2 (increased growth)
this is a CYCLE
What is the purpose of meiosis in the process of gametogenesis?
To actually make germ cells into either haploid egg or sperm
*SEXUAL REPRODUCTION
T/F: The chromosomal number is somatic cells during mitosis are halved
No
___is the process by which the number of chromosomes in a cell
nucleus is halved during the formation of germ cells (eggs and sperm).
Meiosis
“One way process” is used to describe mitosis or meiosis?
meiosis
How many chromosomes does everyone have in every body cell?
46, 23 form mom, 23 from dad
What are the stages of mitosis?
prophase,prometaphase,metaphase,anaphase,telophase,cytokinesis
Explain stage of prophase(mitosis)
During S phase of interphase, our DNA has already duplicated so now we have 46 sister chromatids. Prophase early mitotic spindles start to from between centromeres that are pushing apart
Explain stage of prometaphase(mitosis)
Fragments of nuclear envelopes+ kinetochore microtubules
In anaphase, how many chromosomes are there?
46
What happens during metaphase(mitosis)?
Sister chromatids start to align along metaphase plate
Goal of meiosis I is to ___
separate homologous chromosomes
How many homologous chromosomes are there during meiosis I
23
Before prophase of meiosis I: how many chromosomes
Still 46, 23 form mom an 23 from dad, however, the DNA has replicated so each chromosome is a sister chromatid.
Explain prophase meiosis I
23 homologous chromosomes/tetrads linked by chiasmata, centromeres separate to opposite poles and spindles form
Explain Metaphase Meiosis I
Linking of homologous chromosomes along the metaphase plate, microtubules attach to kinetochore
Explain Anaphase meiosis 1
Homologous chromosomes separate, however, sister chromatids remain attached
T/F: At end of Meiosis 1 there are 2 haploid cells
True
What is the result of Meiosis II?
4 haploid cells
When does DNA replication occur during mitosis and meiosis?
During interphase, before mitosis and meiosis begins
T/F there are 2 division in mitosis
False: 1 division in mitosis and 2 divisions in meiosis
T/F Synapsis of homologous chromosomes occurs during meiosis
Yes, it is the crossing over betweeen nonsister chromatids during prophase 1.
A tetrad is
group of 4 chromatids
How are the daughter cells different between mitosis and meiosis?
Mitosis: 2 daughter cell are diploid (2n), genetically identical to parent
Meiosis: 4 daughter cells that are haploid(23), has half as may chromosomes of parents and are non genetically identical
What is the role of mitosis in the animal body?
Allows zygote to become a multicellular body, produces cells for jobs like tissue repair
What is the role of meiosis in the animal body?
Produce gametes which are haploid meaning they contain a number of chromosomes and also are genetically variable
Why is it favorable to have offspring of varying genotypes?
- one genotype may better enhance reproductive success than another under changing environmental factors
- may enhance adaptive genes, lose unfavorable genes
Name the two ways to generate variation within meiosis.
- Chromosome segregation (Independent Assortment)
- Crossing over (homologous recombination)
What is the formula used to calculate independent assortment in cells undergoing meiosis I?
number of possible orientations= 2^n
n= number of chromosome pairs
2=number of chromosomes in each pair
Crossing over occurs at what step?
Prophase of meiosis I
In a cell with 4 chromosomes, how many sister
chromatids are visible at the end of
telophase/cytokinesis?
0
How much genetic material is present in a cell during
anaphase I compared to a cell during metaphase?
the same amount
Embryonic cells undergo ____, making more diploid cells
mitosis
