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AP Bio > Meiosis > Flashcards

Meiosis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Heredity

A

transmission of traits from one generation to the next

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2
Q

Variation

A

offspring differ somewhat in appearance from parents and siblings

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3
Q

Genetics

A

study of heredity and hereditary variation

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4
Q

Where do offspring acquire genes?

A

parents

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5
Q

Genes

A

coded information, organized into
units that parents pass on to offspring; Genes program specific traits that emerge as we develop; Genes are segments of DNA

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6
Q

allele

A

alternative copy of gene

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7
Q

coding in genes

A

Information is coded in DNA in
sequences of 4 bases
Cells translate these DNA sequences in genes,
programming the cell to make
proteins (including enzymes)
All the proteins working together produces
an organism’s inherited traits
Genes are transmitted from one generation to the next by
sperm + ovum

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8
Q

chromosome numbers

A

DNA is divided into chromosomes, each species has

a specific number

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9
Q

chromosome numbers humans

A 
o  Humans-
46 chromosomes (haploid=23)
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10
Q

Locus

A

gene’s specific
location along the
chromosome

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11
Q

Asexual Reproduction

A

one parent is involved and
passes copies of its genes to offspring. clones. Offspring have
same genome as the parents except for mutations

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12
Q

clone

A

group of

genetically identical individuals produced asexually

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13
Q
  • Sexual Reproduction
A

Two parents give rise to offspring that have combination of their genes
Results in
greater variation

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14
Q

human–somatic cell

A

body cell, contains 46 chromosomes, with two of each type

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15
Q

somatic cell

A

body cell

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16
Q

gamete

A

reproductive/sex cell

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17
Q

Homologous chromosomes

A

chromosomes that make up a
pair, due to
same length, banding pattern, and centromere placement. These two carry genes of the same type. exception: sex chromosomes

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18
Q

sex chromosomes

A

females–xx, males–xy

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19
Q

autosomes

A

non sex chromosomes (22)

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20
Q

46 chromosomes are therefore 2 sets of 23- because?

A

1 set inherited from each parent

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21
Q

Each sperm cell or ovum cell has (chromosomes?)

A

22 autosomes and 1 sex chromosome

single set of 23 chromosomes

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22
Q

haploid cells

A

Gamete cells with one set of chromosomes

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23
Q

Gametes

A

sperm + ovum

24
Q

syngamy

A

Fertilization. haploid sperm fuses with a haploid egg

25
Q

zygote + cell division in zygote

A

fertilized egg. two haploid sets of chromosomes with genes from the mother and the father. Mitosis in zygote produces more diploid somatic cells. Gametes, which develop in gonads, contain half the
number of chromosomes. Meiosis is the process that reduces the chromosome number in half.

26
Q

diploid cells

A

Cells with 2 sets of chromosomes are called diploid cells

2n=46

27
Q

What keeps a species’ chromosome count constant?

A

Fertilization and meiosis alternate in sexual life cycles

28
Q

Meiosis

A

Results in 4 daughter cells, each w 1/2 number of chromosomes as the parent— haploid
Contains two consecutive divisions called Meiosis I and Meiosis II

29
Q

Interphase I

A

Each chromosome replicates, forming

two sister chromatids

30
Q

prophase I

A

Lasts longer than in mitosis
o Synapsis occurs, forming tetrad. Chromatids of homologous chromosomes cross over along their
length, forming chiasmata.
o Centrosomes move apart, spindle fibers start to form and attach to kinetochores
o Nuclear membrane and nucleoli disappear
o Can last for days- 90% of meiosis

31
Q

synapsis

A

as chromosomes condense,

homologous chromosomes, each made of two sister chromatids, come together as pairs

32
Q

tetrad

A

Pairs in synapsis are called tetrad

bc 4 sister chromatids

33
Q

chiasmata

A
  • can

exchange segments of DNA with one another

34
Q

Metaphase I

A

Tetrads arrange on metaphase plate
o Microtubules are
attached

35
Q

Anaphase I

A

o Spindle apparatus pulls apart homologous chromosomes, but
sister chromatids stay attached
o Homologous chromosomes move toward opposite pole

36
Q

Telophase I and Cytokinesis

A

Each pole has haploid chromosome set, but each chromosome
is still
double stranded
o Cytokinesis occurs simultaneously, forming
two daughter cells
o Some species have second interphase, others head straight into
next meiotic division
o No duplication of chromosomes!

37
Q

Random Fertilization

A

each human ovum (from 8 million
possibilities) is fertilized by single sperm (another 8 million
possibilities=
64 trillion possible zygotes

38
Q

Origins of Genetic Variation

A

Sexual life styles produce. Independent Assortment of Chromosomes, Crossing over, Random Fertilization

39
Q

Crossing Over

A

produces individual chromosomes that combine genes in heritage from both parents
o In humans- 2-3 crossing overs occur per chromosome pair

40
Q

Independent Assortment of Chromosomes,

A

during metaphase I, the
chromosomes line up at metaphase plate with
a random orientation of maternal and paternal chromosomes facing the poles
o About 8 million possibilities of combinations (2^23)

41
Q

Prophase II

A

Spindle apparatus forms, chromosomes move toward

metaphase plate

42
Q

metaphase II

A

Chromosomes are lined up on

metaphase plate

43
Q

Anaphase II

A

Centromeres of sister chromatids
separate
o Sister chromatids, now individual chromosomes, move
toward opposite poles

44
Q

Telophase II and Cytokinesis

A

o Nuclei form at opposite poles and cytoplasm
splits
o Concludes with
four daughter cells each w a haploid number of chromosomes

45
Q

unique events of meiosis

A

Synapsis occurs, forming a tetrad of four sister chromatids
(two homologous chromosomes). Chiasmata, or
areas of crossing over, form between the two chromosomes
2- At metaphase I, paired homologous chromosomes line up instead of individual chromosomes
3- At anaphase I, sister chromatids do not separate- instead, homologous chromosomes separate, each still double stranded

46
Q

Meiosis II

A

Meiosis II separates the sister chromatids and is identical to mitosis except for resulting in haploid instead of diploid

47
Q

comparison mitosis meiosis

A

Chromosomes # is
mitosis–diploid–2n meiosis–haploid–n–reduced in half in meiosis but not mitosis
2- Mitosis produces 2 cells that are genetically identical to
parent while meiosis
produces four that differ genetically from the parents and from
each other

48
Q

Spermatogenesis-definition + info

A

process of forming sperm; Takes place in

testes; Begins with spermatogonia

49
Q

testes + info

A

male gonads. in testes, seminiferous tubules have thick wall, the sperm go into the lumen of the walls

50
Q

spermatogonia

A

undifferentiated diploid cells

51
Q

Spermatogenesis process

A

Spermatogonia divide by mitosis throughout his entire lifetime; Some enlarge and become primary spermatocytes, which undergo meiosis, producing haploid gametes. First meiotic division produces two secondary spermatocytes; Second meiotic division produces four spermatids; each spermatid becomes a sperm cell

52
Q

oogenesis–def + info

A

process of ovum formation (pl. ova). Takes place on the ovaries, the female gonads.
Begins with oogonia- undifferentiated diploid cells that form during embryonic development.

53
Q

oogenesis process step one

A

Oogonia develop into primary oocytes during prenatal development. By time of birth, they are in prophase I of meiosis and then enter a resting phase.

54
Q

polar body–

A

small cell that dies

55
Q

oogenesis process step two

A

With onset of puberty, primary oocyte completes the first meiotic division–only one oocyte 1x a month gets ovulated–a couple others complete but end up dying–rest are still in prophase. Forms one polar body and one secondary oocyte, which precedes to meiosis II but stops at metaphase II.

56
Q

oogenesis process step three

A

Second meiotic division (occurs at fertilization) gives rise to total of 3 polar bodies (sometimes first polar body divides again, andante the polar body from secondary oocyte) one ovum

AP Bio (35 decks)

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