Meiosis Flashcards Preview

Bio 233 > Meiosis > Flashcards

Flashcards in Meiosis Deck (45):
1

Consists of 2 major phases:
1. M. phase
2. Interphase

Cell Cycle

2

Mitotic phase: cell division

M phase

3

Chromosomes are being replicated in preparation for cell division

Interphase

4

Consists of G1, S, and G2 phases

Interphase

5

Each chromosome is composed of a single chromatid, containing 1 DNA molecule

G1 (gap) phase

6

Each chromatid is replicated so that each chromosome contains two identical DNA molecules, called sister chromatids

S (synthesis) phase

7

Each chromosome now consists of two sister chromatids

G (Gap 2) phase

8

After S phase, how many copies of each gene would you have in an organism that is normally diploid?

4

9

In an individual who is heterozygous at a locus, how many copies of each allele would you find following S phase?

2

10

Are sister chromatids identical?

Yes

11

Are homologous chromosomes identical?

No

12

Two successive divisions of a cell after only one round of DNA replication

Meiosis

13

Formation of haploid gametes in animals

Gametogenesis

14

Formation of haploid spores in plants and fungi

Sporogenesis

15

Prior to meiosis, DNA replicates during ____ phase by way of the replication processes we have already discussed.

S

16

Chromosomes condense; synapse formation
-2n

Prophase I

17

Independent assortment; line up along metaphase plate

Metaphase I

18

Separation of homologous chromosomes

Anaphase I

19

Crossing over occurs during _____?

Prophase I

20

Produce new allele combinations in a chromatid

Genetic recombination

21

Cross-like structure where crossing over occurs

Chiasma

22

Two chromosomes pared up; align according to areas of homology

Synapse

23

Homologous pair of chromosomes each with 2 sister chromatids

Tetrad

24

Genetic significance of Meiosis

1. Each gamete at the end of meiosis carries only one copy of each chromosome
2. In meiosis I, homologous chromosomes end up at one pole or the other at random
3. In meiosis I, chromosomes don't influence each other's segregation
4. Crossing over between maternal and paternal homologs during meiosis I creates new allele combinations

25

Crosses between true-breeding strains of peas with alternative forms of a single trait; genotype peas had was homozygous; each diploid organism can have up to 2 alleles for each gene

Mendel's Law of Segregation monohybrid crosses

26

Masking of traits

Dominance

27

Different alleles arise through______.

Mutations

28

Loss of function mutation and gain of function mutation

How dominance occurs at the molecular level

29

Principle of Segregation

*Recessive traits, which are masked in the F1 generation, reappear in the specific proportion of the F2
*Two alleles segregate from each other during the formation of the gametes in anaphase I in meiosis
*Half of gametes get one allele, other half get other allele
*Then the union of gametes is random

30

Cross of unknown genotype possessing the dominant phenotype with a known homozygous recessive individual (tester)

Testcross

31

Test to know if an individual with a dominant phenotype is homozygous or heterozygous.

Testcross

32

All progeny from testcross show the dominant phenotype

Unknown is homozygous

33

Progeny from testcross show approximately 1:1 dominant to recessive phenotype

Unknown is heterozygous

34

If a mous has a dominant phenotype (P-), how would you determine if it is homozygous (PP) or heterozygous (Pp)?
a. Cross it to a homozygous dominant mouse
b. Cross it to a mouse with the dominant trait but a similarly unknown genotype
c. Cross it to a mouse with the recessive trait
D. Cross it to a heterozygous dominant mouse
E. It cannot be determinded

c. Cross it to a mouse with the recessive trait

35

Principle of Independent Assortment

*The two causative genes for two pairs of traits assort independently of one another
*Pairs of alleles for genes on different chromosomes segregate independently in the formation of gametes during meiosis

36

*Line up along metaphase plate is random
*Chromosomes pull apart separately from one another

How meiosis explains independent assortment

37

How many different types of gametes can be formed by the genotype AaBbCc?
a. 3
b. 4
c. 8
d. 16
e. 32

c. 8

38

The probability of two independent events occurring simultaneously is the product of their individual probabilities
-"and"

Product Rule

39

The probability of either one of several independent, mutually exclusive events is the sum of their individual probabilities
-"or"

Sum Rule

40

The probability that a situation will occur when there are multiple ways to get a combination

Binomial theorem

41

Dominant Human diseases that follow Mendelian inheritance

-Achondroplastic dwarfism: caused by interference by interference in bone development; gain of function mutation
-Huntington's disease: loss of function mutation

42

Recessive Human diseases that follow Mendelian inheritance

-Caused by loss of function mutation
-Albinism
-PKU: Missing enzyme that breaks down phenylalaine
-Cystic Fibrosis
-Tay Sachs
-Sickle Cell Anemia

43

Pedigree Symbols:
1. Circle
2. Square
3. Diamond
4. Shaded symbol
5. Double bonded line between symbols
6. Single bonded line between M and F
7. Branched connection between symbols
8. Proband
9. Slash through symbol
10 .Dot in symbol
11. Roman Numerals

1. Female
2. Male
3. Unknown sex
4. Affected individual
5. Consanguineous parents (related)-up to 2nd cousins
6. Parents (unrelated)
7. Siblings
8. Patient, person of interest
9. Deceased individual(s)
10. Heterozygous carrier
11. Succesive generations

44

Mode of inheritance where in a pedigree, a generation was skipped and then the dominant trait came back.

Recessive

45

Mode of inheritance where in a pedigree, the affected patients in each generation are not sex-linked and it appears in a 50% chance in each generation.

Dominant autosomal