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AP Biology Semester 1 > Chapter 13 > Flashcards

Chapter 13 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

gentics

A

the scientific study of heredity and variation

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2
Q

heredity

A

The transmission of traits from one generation to the next

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3
Q

variation

A

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

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4
Q

true or false: it is genes that are actually inheritied

A

TRUE

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5
Q

genes

A

units of heredity, are made up of segments of DNA

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6
Q

how are genes passed on to the next generation?

A

via reproductive cells called gametes

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7
Q

locus

A

the specific location a gene has on a certain chromosome

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8
Q

DNA is packaged into…

A

a chromosome

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9
Q

asexual reproduction

A

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

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10
Q

clone

A

a group of genetically identical individuals from the same parent

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11
Q

sexual reproduction

A

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

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12
Q

life cycle

A

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

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13
Q

somatic cells have how many pairs of chromosomes?

A

23 pairs

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14
Q

karyotype

A

an ordered display of the pairs of chromosomes from a cell

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15
Q

homologous chromosomes

A

two chromosomes in each pair

-same length, shape, and carry genes controlling the same inherited characters

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16
Q

sex chromosomes

A

determine the sex of an individual, called x and y

  • females have pair of x chromosome
  • males have one x chromosome and one y chromosome
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17
Q

the remaing 22 pairs of chromosomes apart from the sex chromosomes are called

A

autosomes

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18
Q

each pair of homologous chromosomes include…

A

one chromosome from each parent

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19
Q

the 46 chromosomes in a human somatic cell are two sets of 23; one from _____ and one from _____

A

mother

father

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20
Q

diploid cell

A

has two sets of chromosomes

for humans the diploid number is 46

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21
Q

haploid cell

A

this is a gamete that contains a single set of chromosomes

  • from humans, the haploid number is 23
  • -22 autosomes and 1 sex chromosome
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22
Q

an unfertilized egg always has the chromosome..

A

x

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23
Q

true or false;

a sperm cell, may have either x or y chromosome

A

true

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24
Q

fertilization

A

the union of gametes (sperm and egg)

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25
Q

zygote

A

fertilized egg

  • has one set of chromosome from each parent
  • zygote produces somatic cells by mitosis and develops into an adult
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26
Q

when do people start to produce haploid gametes?

A

at sexual maturity

27
Q

meiosis

A

results in one set of chromosome in each gamete

28
Q

alternation of generations (by plants and some algae)

A
  • includes both a diploid and a haploid multicellular stage
  • the diploid organism, called the sporophyte, makes haploid spores by meiosis
  • ea. spore grows by mitosis into a haploid organism called a gametophyte
  • a gametophyte makes haploid gametes by mitosis
  • fertilization of gametes result in a diploid sporophyte
29
Q

alternation of generations (by fungi and protists)

A
  • In most fungi and some protists, the only diploid stage is the single-celled zygote; there is no multicellular diploid stage
  • The zygote produces haploid cells by meiosis
  • Each haploid cell grows by mitosis into a haploid multicellular organism
  • The haploid adult produces gametes by mitosis
30
Q

true or false: only diploid cells can divide by mitosis

A

FALSE

depending on the type of life cycle, either haploid or diploid cells can divide by mitosis

31
Q

true or false: only diploid cells can undergo meiosis

A

true

32
Q

meiosis takes place in two sets of cell divisions….

A
  1. Meiosis 1

2. Meiosis 2

33
Q

the two cell divisions result in ___ daughter cells

and each daughter cell has _______

A
  • four

- only half as many chromosomes as the parent cell

34
Q

what happens in Meioisis 1:

A

(reductional division): homologous chromosomes pair up and separate, resulting in two haploid daughter cells with replicated chromosomes

35
Q

what happens in Meiosis 2:

A

(equational division) sister chromatids separate

—the result is four haploid daughter cells with unreplicated chromosomes

36
Q

what happens in the interphase of meiosis?

A
  • pair of homologous chromosomes in diploid parent are duplicated
  • starts as / / and now is // //
  • two pairs of sister chromatids
37
Q

what are the four phases of meiosis 1

A

prophase 1
metaphase 1
anaphase 1
telophase 1 and cytokinesis

38
Q

what happens in prophase 1 of meiosis?

A
  • crossing over and synapsis

- homologous chromosomes loosley pair up, aligned gene by gene

39
Q

synapsis

A

homologous chromosomes loosely pair up, aligned gene by gene

40
Q

crossing over

A
  • nonsister chromatids exchange DNA segments

- each pair of chromosomes form a tetrad, a group of four chromatids

41
Q

chismata

A

x shaped regions where crossing over occured

42
Q

what happens in Metaphase 1 of meiosis 1

A
  • tetrads line up at the metaphase plate, with one chromosome facing each pole
  • microtubules from one pole are attached to the kinetochore of one chromosome at each tetrad
  • microtubules from the other pole do the same
43
Q

what happens in anaphase 1 of meiosis 1

A
  • pair of homologous chromosomes separate
  • one chromosome moves toward each pole, guided by the spindle aparatus
  • sister chromatids remain attached at the centormere and move as one unit toward the pole
44
Q

what happens in telophase 1 and cytokinesis

A
  • each half of the cell has a haploid set of chromosomes; each chromosome still consists of two sister chromatids
  • cytokinesis happens simultaneously
  • no chromosome replication occurs between the end of meiosis 1 and the beginning of meiosis 2 because the chromosomes are already duplicated
45
Q

what are the four phases of meiosis 2

A
  • prophase 2
  • metaphase 2
  • anaphase 2
  • telophase 2 and cytokinesis
46
Q

what happens in prophase 2

A
  • a spindle apparatus forms

- chromosomes move toward metaphase plate

47
Q

what happens in metaphase 2

A
  • sister chromatids are arranged at the metaphase plate

- The kinetochores of sister chromatids attach to microtubules extending from opposite poles

48
Q

because of crossing over in meiosis 1 the two sister chromatids of each chromosomes are ….

A

no longer genetically identical

49
Q

what happens in anaphase 2

A
  • sister chromatds separate

- The sister chromatids of each chromosome now move as two newly individual chromosomes toward opposite poles

50
Q

what happens in telophase 2

A
  • the chromosomes arrive at opposite poles

- nuclei form, and chromosomes begin decondensing

51
Q

what do you have at the end of meiosis 2

A
  • 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
52
Q

where does DNA replication occur in mitosis versus meiosis

A

both occur in interphase

53
Q

number of divisions in mitosis versus meiosis

A

one in mitosis

two in meiosis

54
Q

when does synapsis of homologous chromosomes occur in mitosis versus meiosis

A

does not occur in mitosis
-Occurs during prophase I along with crossing over between nonsister chromatids; resulting chiasmata hold pairs together due to sister chromatid cohesion

55
Q

number of daughter cells and genetic composition in mitosis versus meiosis

A

two daughter cells in mitosis and genetically identical to the parent cell
-in meiosis it is four,ach haploid (n), containing half as many chromosomes as the parent cell; genetically different from the parent cell and from each other

56
Q

what is the role in the animal body of the final product of mitosis versus meiosis

A
  • in mitosis it enables multicellular adult to arise from zygote; produces cells for growth, repair, and, in some species, asexual reproduction
  • in meiosis it produces gametes; reduces number of chromosomes by half and introduces genetic variability among the gametes
57
Q

what are three events that are unique to meiosis (and all three occur in meiosis 1)

A

– Synapsis and crossing over in prophase I:
Homologous chromosomes physically connect and exchange genetic information
– At the metaphase plate, there are paired homologous chromosomes (tetrads), instead of individual replicated chromosomes
– At anaphase I, it is homologous chromosomes, instead of sister chromatids, that separate

58
Q

what allows sister chromatids of a single chromosome stay together meiosis 1

A
  • sister chromatid cohesion

- -protein complexes called cohesins are responsible for this cohesion

59
Q

when is the sister chromatid cohesion split? (mitosis versus meiosis)

A

In mitosis, cohesins are split at the end of metaphase
• In meiosis, cohesins are split along the chromosome arms in anaphase I (separation of homologs) and at the centromeres in anaphase II (separation of sister chromatids)

60
Q

alleles

A

mutations (changes in an organism’s DNA) create different versions of genes which are alleles
-shuffling of alleles during sexual reproduction produces genetic variation

61
Q

what three things contribute to genetic variation?

A
  • independent assortment of chromosomes
  • crossing over
  • random fertilization
62
Q

homologous pairs of chromosomes orient randomly at ______ of meiosis

A

metaphase 1

63
Q

when does crossing over occur?

A

begins very early in prophase 1, as homologous chromosomes pair up gene by gene

AP Biology Semester 1 (21 decks)

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