genetics

Question 1

what are the stages of mitosis

Answer 1

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Question 2

interphase I

(4)

Answer 2

• Chromosomes replicate
• Chromosome consists of 2 identical sister chromatids held together by a centromere
• Centrioles move towards opposite poles of the cell
• chromatin condense into chromosomes

Question 3

prophase I

(4)

Answer 3

• Chromosomes condense & come together in homologous pairs (synapsis)
• Each pair is composed of 4 chromatids, they form a tetrad
• Crossing over occurs & permits the exchange of genetic material between homologous pairs
• Nuclear membrane disintegrates

Question 4

metaphase I

(2)

Answer 4

• Pairs of homologous chromosomes (homologues) line up at the equator by independent assortment
• Spindle fibres attach to centromere

Question 5

anaphase I

(2)

Answer 5

• Homologues separate, one of each pair going to each pole of the cell
• Sister chromatids do not separate; they are still attached by a centromere

Question 6

telophase I & cytokinesis

(3)

Answer 6

• Two clusters of chromosomes have formed, each containing one member of each pair homologues
• Cytokinesis occurs
• There is little or no interphase between meiosis I and meiosis II

Question 7

prophase II

(2)

Answer 7

• Chromosomes have relaxed after telophase. They recondese
• Spindle fibers reform

Question 8

metaphase II

(2)

Answer 8

• Sister cromatids line up along the metaphase plate
• Spindle fibres attach at the centromere

Question 9

anaphase II

(2)

Answer 9

• Spindle fibres shorten and sister chromatids separate and are now individual chromotids
• Move towards opposite poles

Question 10

telophase II & cytokinesis

(2)

Answer 10

• Spindle fibres disappear; the nuclear membrane and nucleus reform
• After cytokinesis, 4 unique daughter cells have formed, each with a haploid number (n) of chromosomes

Question 11

how many chromsomes do somatic cells have

Answer 11

46

Question 12

how many chromosomes do gametes have

Answer 12

23

Question 13

genotype

Answer 13

The combination of alleles for a trait e.g., Rr. The collection of alleles that an individual contains (i.e., the letter ‘code’)

Question 14

phenotype

Answer 14

The physical appearance of a trait. It is based on genotype; e.g., RR and Rr can be described as round pea seeds; whereas rr can be described as a wrinkled pea seed.

Question 15

allele

Answer 15

the alternate forms of a gene

Question 16

gene

Answer 16

sections of DNA that contain genetic information for the inheritance of specific traits

Question 17

dominant

Answer 17

The form of a trait that will always appear (be expressed) when an individual has an allele for it.

Question 18

recessive

Answer 18

The form of a trait that will only appear (be expressed) if the individual has 2 alleles for it.

Question 19

trait

Answer 19

a specific characteristic stored within the genetic material of an organism, that determines some specific aspect of how it looks or behaves.

Question 20

diploid

Answer 20

refers to twice the number of chromosomes in a gamete (2n). Every cell of the body is diploid except the sex cells.

Question 21

haploid

Answer 21

a cell with half the number of chromosomes as parent cell, referred to as n

Question 22

homozygous

Answer 22

describes the genotype of an individual with two alleles that are the same

Question 23

heterozygous

Answer 23

describes the genotype of an individual with two alleles for the same gene that are different

Question 24

co-dominance

Answer 24

a pattern of inheritance where both alleles are expressed at the same time (spots or stripes)

Question 25

complete dominance

Answer 25

when one allele is fully dominant over the other. The trait displayed will be dominant if the child is monohybrid (AA) or dihybrid (Aa)

Question 25

incomplete dominance

Answer 25

no allele is either dominant or recessive (blending)

Question 26

homologous chromosomes

Answer 26

paired chromosomes similar in size and gene arrangement, but different alleles

Question 27

sister chromatids

Answer 27

a chromosome and its duplicate, attached to one another by a centromere

Question 28

monohybrid cross

Answer 28

A cross where only one trait is being tested

Question 28

dihybrid cross

Answer 28

A cross where two traits are being tested

Question 29

non-disjunction

Answer 29

The failure of chromosomes to separate properly

Question 29

trisomy

Answer 29

inheriting one extra chromosome can result in various syndromes

Question 30

trisomy 21

Answer 30

down

Question 31

trisomy 18

Answer 31

edward

Question 32

trisomy 13

Answer 32

patau

Question 33

XXY

Answer 33

klinefelter

Question 34

XYY

Answer 34

jacobs

Question 35

XXX

Answer 35

triple X

Question 36

monosomy

Answer 36

inheriting one less chromosome

Question 37

XO

Answer 37

turner