Chapter 10 Meiosis Flashcards

1
Q

Heredity

A

Transmission of traits from one generation to the next

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2
Q

Variation

A

Differences by the differences in appearance that offspring show from parents and siblings

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3
Q

Genetics

A

Scientific study of heredity and variation

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4
Q

Units of heredity made of segments of DNA

A

Genes

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5
Q

Gametes

A

Reproductive cells

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6
Q

Most DNA is packaged in

A

Chromosomes

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7
Q

Somatic cells

A

The cells of the body except for gametes

Humans have 46 chromosomes in their somatic cells

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8
Q

Each gene has a specific position or_____, on a certain chromosome

A

Locus

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9
Q

In________, a single individual passes genes to its offspring without the fusion of gametes

A

Asexual

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10
Q

A_______is a group of genetically identical individuals from the same parent

A

Clone

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11
Q

In _________reproduction, two parents give rise to unique offspring that have unique combinations of genes inherited from the two parents

A

Sexual

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12
Q

A__________ is the generation to generation sequence of stages in the reproductive history of an organism

A

Life cycle

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13
Q

Human somatic cells have _______pairs of chromosomes

A

23

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14
Q

A________is an ordered display of the pairs of chromosomes from a cell

A

Karyotype

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15
Q

The two chromosomes in each pair are called

A

Homologous chromosomes or homologs

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16
Q

Chromosomes in a homologous pair are the same _______ and Carey genes controlling the same _______characters

A

Length, inherited

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17
Q

Sex chromosomes are called

A

X and Y

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18
Q

The remaining 22 pairs of chromosomes are called

A

Autosomes

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19
Q

Each pair of homologous chromosomes include one chromosome from each

A

Parent

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20
Q

A _______ (2n) has two sets of chromosomes

A

Diploid cell

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21
Q

Human diploid number is

A

46

2n=46

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22
Q

A gamete contains a single set of chromosomes and is

A

Haploid(n)

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23
Q

Human haploid number is

A

23

Each set contains 22 autosomes and a single sex chromosome

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24
Q

In an egg the sex chromosome is

A

X

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25
Q

In a sperm cell the sex chromosome is

A

Either X or Y

26
Q

The union of gametes

A

Fertilization

27
Q

The fertilized egg is called a

A

Zygote

28
Q

The _______produces somatic cells by mitosis and develops into an adult

A

Zygote

29
Q

_________are the only type of human cells produced by meiosis

A

Gametes

30
Q

Meiosis results in ______set of chromosomes in each gamete

A

One

31
Q

Gametes undergo no further __________ before fertilization

A

Cell division

32
Q

Gametes fuse to form a

A

Diploid zygote

33
Q

Plants and some algae exhibit an alternation of

A

Generations

The life cycle includes both diploid and haploid organisms

The diploid organism is called a sporophyte makes haploid spores by meiosis

34
Q

Meiosis takes place in two sets of cell divisions

A

Meiosis I and meiosis II

35
Q

Meiosis results in

A

Four daughter cells

36
Q

Each daughter cell in meiosis has ________ as many chromosomes as the parent cell

A

Half

37
Q

The diploid organism (plants and some algae) called a _________ makes haploid spores by mitosis

A

Sporophyte

38
Q

Each spore grows by mitosis into a haploid organism called a

A

Gametophyte

39
Q

In most fungi and some protist, the only diploid stage is the single called

A

Zygote-there is no multicellular diploid stage

40
Q

Only _______cells can undergo meiosis

A

Diploid

41
Q

Interphase I

A

Meiosis is preceded by an interphase in which each of the chromosomes replicates.

The result is sister chromatids that remain attached at their centromere

42
Q

Prophase I

A

Chromosomes begin to condense

Homologous chromosomes pair up (synapsis) aligned gene by gene

At numerous places chromatids of homologous pairs are crisscrossed in regions called chiasmata

Centrosomes begin to move away

Nuclear envelope and nucleoli disperse

43
Q

Metaphase I

A

Homologous chromosome pairs are arranged along metaphase plate

Kinetochore microtubules from one pole of the cell are attached to one chromosome of each pair

44
Q

Anaphase I

A

Pairs of homologous chromosomes separate

Sister chromatids remain attached at the centromere and move as one unit toward the pole

45
Q

Telephase I and Cytokinesis

A

Each half of the cell has a haploid set of chromosomes

Each chromosome still consists of two sister chromatids

Cytokinesis usually occurs simultaneously forming two haploid daughter cells

46
Q

In animal cells, a cleavage furrow forms and in plant cells

A

A cell plate forms

47
Q

No chromosome replication occurs between Meiosis I and Meiosis II because

A

The chromosomes are already replicated

48
Q

Meiosis II phases

A

Pro II
Meta II
Ana II
Telo II

49
Q

Prophase II

A

Spindle apparatus forms and the chromosomes move toward metaphase plate

50
Q

Metaphase II

A

Sister chromatids are arranges at metaphase plate

Because of crossing over in Meiosis I, the two sister chromatids are no longer genetically identical

The kinetochores of each sister chromatids are pointing towards opposite poles

51
Q

Anaphase II

A

The centromeres of the sister chromatids finally separate and the sister chromatids of each pair, now chromosomes, move towards opposite poles of the cell

52
Q

Telephase II and Cytokinesis

A

Nuclei form and chromosomes begin decondensing

There are four daughter cells each with a haploid set of unreplicated chromosomes

Each daughter cell is genetically distinct from the others and from the parent cell

53
Q

A zipper like structure forms during prophase I when homologous pairs align

A

Synaptonemal complex

54
Q

Three events unique to Meiosis

A

Synapsis and crossing over in prophase I

Alignment of homologous pairs at the metaphase plate in Metaphase I

Separation of homologs in anaphase I

55
Q

In meiosis sister chromatids stay together due to sister chromatid cohesion. In mitosis cohesins are cleaves during

A

Metaphase

56
Q

In meiosis, cohesins are cleaved along the chromosome arms in ________, and at the centromeres in __________

A

Anaphase I, anaphase II

57
Q

_________are the original source of genetic diversity

A

Mutations

58
Q

Mutations create different versions of genes called

A

Alleles

59
Q

Three mechanisms contribute to genetic variation

A

Independent assortment of chromosomes

Crossing over

Random fertilization

60
Q

The number of combinations possible when chromosomes assort independently into gametes is

A

2^n where n is the haploid number

For humans there are more than 8 million combinations of chromosomes

61
Q

Recombinant Chromosomes

A

Combine DNA from each parent and occurs during crossing over

In Humans, one to three crossover events per chromosome pair

62
Q

What is the diploid stage of a plant that follows fertilization called?

A

Sporophyte