5.2

Question 1

Gametes

Answer 1

meiosis yields one oocyte and 3 polar bodies (XX) or 4 sperm cells (XY)

Question 2

Meiosis

Answer 2

Interphase: replication of chromosomes (46 X, one diploid set)

Meiosis I: first meiotic division (23 X, one haploid set) 2 cells

Meiosis II: second meiotic division (23 I, one haploid set) 4 gametes

Question 3

Meiosis I (reductional division)

Answer 3

Prophase I: homologous chromosomes condense and undergo synapsis (pairing homologous X) and crossing over (recombinant chromatids) (2S, 2C) also spindle formation and nuclear envelope break down

Metaphase I: tetrads (2X) line up, each homologous X is attached at centromere

Anaphase I: homologous chromosomes separate but not sister chromatids

Telophase 1: 2 daughter cells, slightly uncondense, slight nuclear envelope reform (1S, 2C)

Question 4

Meiosis II (equational division)

Answer 4

Prophase II: condense, nuclear envelope break down, spindle formation
Metaphase II: chromosomes align, microtubules attach
Anaphase II: sister chromatids seperate
Telophase II: cytokinesis, nuclear envelope reforms

Question 5

chromosome number variation

Answer 5

• first division nondisjuction: 2 gametes missing X, 2 gametes extra X
• second division nondisjunction: 1 gamete missing X, 1 gamete extra X, 2 gamete ‘normal’

Question 6

medel studied which traits of which plants

Answer 6

Pea plants, 7 traits:
- color of seed
- shape of seed
- color of pod
- shape of pod
- color of flower
- position of flower
- plant height

Question 7

names of generations

Answer 7

P: parental
F: filial

Question 8

punnet square

Answer 8

we love punnet squares, know how to draw them, capital is dominant gene (A) lower case is recessive (a)
- monohybrid cross: one trait
- dihybrid cross: 2 traits

Question 9

Mendels laws of inheritance

Answer 9

1. Law of dominance: hybrid offspring only inherit dominant trait
2. Law of segregation: offspring aquire one factor from each parent
3. Law of independant assortment: pairs of traits assort independently (only applies to genes located on different chromosomes)

Question 10

wrinkled vs smooth seed

Answer 10

found in SBE1 gene, in wrinkled peas it’s interrupted, cannot convert sugar to starch, young seed swells then adult seed deflates looking wrinkled