Biology_Week 8 - Mitosis Meiosis

Front 1

What distinguishes living organisms?

Back 1

Ability to reproduce their OWN kind

Front 2

What is heredity?

Back 2

transmission of traits from one generation to the next

Front 3

What is special about meiosis?

Back 3

germ cells divide to make egg or sperm, SEXUAL REPRODUCTION in plants and animals

Front 4

What are germ cells?

Back 4

Cells that give rise to gametes

Front 5

What is required for sexual reproduction?

Back 5

unique cominations of genes inherited from both parents

Front 6

What is similar about offspring?

Back 6

same pool ofDNA

Front 7

What is varied about offspring?

Back 7

mixes of parental DNA differ from siblings

Front 8

What are genes?

Back 8

Segments of DNA

Front 9

How many complete sets of genes is passed to offspring? and in what?

Back 9

One, gamete (sperm or egg)

Front 10

What causes gametes to unite?

Back 10

Fertilization

Front 11

What does ploidy refer to?

Back 11

The number of "sets" of genetic material

Front 12

What should be included in one complete set?

Back 12

one of every type of chromosome, one of every kind of gene

Front 13

Can organisms have more than one set of genes?

Back 13

yes, for example humans have two

Front 14

Why do organisms have more than one set of genes?

Back 14

Backup genes if one is "bad" or mutated

Front 15

Haploid

Back 15

n

Front 16

Diploid

Back 16

2n

Front 17

Triploid

Back 17

3n

Front 18

Tetraploid

Back 18

4n

Front 19

Humans are what?

Back 19

diploid (2n)

Front 20

Each human somatic cell has how many chromosomes? How many pairs?

Back 20

46 chromosomes, 2 sets

Front 21

What is a homologous chromosome?

Back 21

a set of one maternal chromosome and one paternal chromosome that pair up with each other inside a cell during meiosis. Humans have 23 pairs of homologs.

Front 22

How many copies of each gene does each human have?

Back 22

2 copies

Front 23

Sex Chromosomes

Back 23

X and Y chromosomes

Front 24

Females

Back 24

XX

Front 25

Males

Back 25

XY

Front 26

Autosomes

Back 26

All non-sex chromosomes. 22 pairs of autosomes, 1 pair of sex chromosomes.

Front 27

Where do we get homologous chromosomes?

Back 27

One whole set from father (haploid, 23), one whole set from mother (haploid, 23), diploid (2n, 46)

Front 28

What is a Karotype?

Back 28

A picture of a person's chromosomes. Can be observed in Prophase or Metaphase of Meiosis

Front 29

Gametes are haploid or diploid?

Back 29

haploid

Front 30

Gametes contain how many sets of chromosomes?

Back 30

one

Front 31

In an unfertilized egg the sex chromosome is always what?

Back 31

X

Front 32

In a sperm cell the sex chromosome is what?

Back 32

X or Y

Front 33

Which parent determines sex of the offspring?

Back 33

Male

Front 34

Somatic cells are all body cell except which?

Back 34

The germ cells that produce gametes

Front 35

Where do germ cells reside?

Back 35

Ovaries and the testes

Front 36

What cell type is only produced by meiosis? Haploid or diploid?

Back 36

Gametes, haploid

Front 37

Meiosis results in how many sets in each gamete?

Back 37

One

Front 38

What restores diploid condition? What is formed?

Back 38

Fertilization, zygote

Front 39

How many of each homologous pair per gamete?

Back 39

1 of each pair

Front 40

Meiosis involves replicating how many times? Dividing how many times?

Back 40

Replicate once, divide twice

Front 41

Meiosis is preceded by what?

Back 41

replication of chromosomes

Front 42

How many cell divisions in Meiosis?

Back 42

two: meiosis I and meiosis II

Front 43

What is the result of meiosis?

Back 43

four daughter cells with half as many chromosomes as the parent cell

Front 44

What happens in Meiosis I?

Back 44

homologous chromosomes seperate

Front 45

What is the result of Meiosis I?

Back 45

two haploid daughter cells with replicated chromosomes

Front 46

What happens in Meiosis II?

Back 46

sister chromatids seperate

Front 47

What is the result of Meiosis II?

Back 47

four haploid daughter cells with unreplicated chromosomes

Front 48

Meiosis I: Prophase I: Similarities compared to Mitosis

Back 48

duplicated chromosomes begin to condense; nuclear envelope breaks down; spindle forms

Front 49

Meiosis I: Prophase I: Differences compared to Mitosis

Back 49

Synapsis: homologous chromosomes pair up, connected, forming a tetrad

Front 50

Meiosis I: Prophase I: Crossing over

Back 50

non-sister chromatids of homologs exchange DNA segments, crossing over sections called CHIASMATA

Front 51

Meiosis I: Metaphase I

Back 51

Tetrads line up at metaphase plate

Front 52

Meiosis I: Anaphase I

Back 52

Pair of homologs seperate = REDUCTION DIVISION

Front 53

Meiosis I: Telophase I & Cytokinesis

Back 53

no chromosome replication occurs between the end of meiosis I and the beginning of meiosis II

Front 54

Meiosis II: Metaphase II

Back 54

two sister chromatids of each chromosome are no longer genetically identical

Front 55

Meiosis II: Anaphase II

Back 55

Sister chromatids of each chromosome are now two individual chromosomes

Front 56

Meiosis II: Telophase II & Cytokinesis

Back 56

Nuclei form, chromosomes decondense, cytokinesis seperates cytoplasm

Front 57

Meiosis II result

Back 57

four haploid daughter cells; each daughter cell is genetically distinct from the other and from the parent cell

Front 58

Mitosis, Meiosis: DNA Replication

Back 58

Interphase, Interphase

Front 59

Mitosis, Meiosis: Divisions

Back 59

One, Two

Front 60

Mitosis, Meiosis: Synapsis and crossing over?

Back 60

No, Yes (Prophase I)

Front 61

Mitosis, Meiosis: Daughter cells, genetic composition

Back 61

2 (identical to parent cell), 4 (all different)

Front 62

Mitosis, Meiosis: Role in animal body

Back 62

Cell reproduction, sexual reproduction by production of gametes

Front 63

Mitosis conserves what?

Back 63

number of chromosomes sets, daughter cells are genetically indentical to parent

Front 64

Meiosis reduces what?

Back 64

number of chromosome sets (diploid - haploid), daughter cells differ genetically

Front 65

What steps are unique to meiosis I?

Back 65

Synapsis and crossing over (prohpase 1), Paired homologous chromosomes (tetrads) line up (metaphase 1); Homologous chromosomes (not sister chromatids) seperate in Anaphase 1

Front 66

Origins of genetic variation

Back 66

Crossing Over; Independent assortment of chromosomes; Random fertilization

Front 67

Mutations

Back 67

create different version of genes; the original source of genetic variation

Front 68

What is crossing over?

Back 68

homologous portions of two non-sister chromatids trade places

Front 69

What does crossing over produce?

Back 69

recombinant chromosomes

Front 70

How does crossing over contribue to genetic variation?

Back 70

combines DNA from two (grand)parents into a single chromosome in the gamete

Front 71

What is independent assortment?

Back 71

Homologous pairs of chromosomes (as tetrads) line up randomly at metaphase 1 of meiosis. (2^23 in humans)

Front 72

What is random fertilization?

Back 72

an sperm can fuse with any ovum (2^23 x 2^23) possible combinations.

Front 73

What is the role of natural selection?

Back 73

results in accumulation of particular genetic variations favored by the environment

Front 74

Where do you find sister chromatids in cell cycle?

Back 74

Check the answer to this question elsewhere, lecture inconclusive