LESSON 6 Flashcards

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1
Q

in mitosis, Daughter cells are genetically ______ to parent cell – same kind and number of ______

A

identical ; chromosomes

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2
Q

Mitosis occurs in ____ or body cells

A

somatic

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3
Q

This is called its _____ number or the total number of chromosomes in a somatic cell.

A

diploid

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4
Q

Diploid means “_____” and is written as “2N”.

A

2 sets

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5
Q

the process in which the number of chromosomes in the original cell is reduced by HALF through the separation of homologous chromosomes

A

meiosis

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6
Q

meiosis is the process in which the number of chromosomes in the original cell is reduced by ____ through the separation of _____ chromosomes

A

HALF ; homologous

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7
Q

Meiosis occurs in _______ only

A

sex organs

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8
Q

Males (___) – sex organs are the ___ in humans
Females (___) – sex organs are the ___ in humans

A

XY - testes
XX - ovaries

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9
Q

Meiosis produces ___ cells – cells with ___ the number of chromosomes as the original cell

A

sex ; ½

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10
Q

Males – meiosis produces _____
Females – meiosis produces ______

A

4 sperm ; 1 (viable) egg

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11
Q

Females – meiosis produces 1 (viable) egg
The other 3 cells are called ______ – they give up their _____ to nourish the 1 good egg.

A

polar bodies ; cytoplasm

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12
Q

Egg and sperm (sex cells) are also called _____

A

gametes

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13
Q

Gametes have ½ the number of chromosomes as somatic (body) cells. We call this the haploid number. Haploid means “____” and is written as “N”.

A

1 set

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14
Q

If human diploid number is 46, what is its haploid number? ____

A

23

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15
Q

*When does meiosis occur in humans?
1.Males beginning at _____
2.Females ______ – all eggs are produced before birth and at puberty eggs mature

A

puberty ; before birth

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16
Q

Nuclear membrane and nucleolus disappear

A

prophase 1

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17
Q

Each chromosome is composed of two sister chromatids held together by a centromere and is called _____.

A

dyad

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18
Q

Crossing over takes place between two non- sister chromatids

A

prophase 1

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19
Q

Each chromosome is composed of two sister chromatids held together by a centromere and is called dyad.

A

prophase 1

20
Q

one from the father and one from the mother); along a point called chiasma (plural, chiasmata)

A

crossing over

21
Q

crossing over takes place between two non-sister chromatids, one from the father and one from the mother); along a point called _____ (plural, chiasmata)

A

chiasma

22
Q

a pair of homologous chromosomes

A

tetrad

23
Q

site of synapsis and crossing over

A

chiasma

24
Q

homologous pairs of chromosomes align along the center of the cell

A

metaphase 1

25
Q

Spindle fibers increase in number and attach to the kinetochore of each chromatid to facilitate movement.

A

metaphase 1

26
Q

separation of daughter chromosomes

A

anaphase 1

27
Q

sister chromatids attached to the centromere

A

anaphase 1

28
Q

at this stage, there are 46 double stranded chromosomes, which is equivalent to 92 chromatids.

A

anaphase 1

29
Q

The two daughter cells are completely divided.

A

telophase 1

30
Q

The number of chromosomes in both cells is the same.

A

telophase 1

31
Q

This is the short pause between meiosis I and meiosis II.

A

interkinesis

32
Q

This is similar to interphase of mitosis, except that, here, there is no replication of chromosomes.

A

interkinesis

33
Q

At this stage, there are 23 double stranded chromosomes, which is equivalent to 46 chromatids

A

prophase 2

34
Q

Each chromosome is composed of two sister chromatids that are joined by a centromere and are attached to the spindle fiber

A

metaphase 2

35
Q

The sister chromatids are now called sister chromosomes as they move toward the opposite poles.

A

anaphase 2

36
Q

The cleavage furrow eventually produces a total two daughter cells, each with a haploid set of chromosomes.

A

telophase 2

37
Q

Homologous (matching) chromosomes pair up before _____

A

1st cell division

38
Q

Homologous chromosomes:

A

-look alike
-code for same traits
-receive one from each parent

39
Q

During 1st division, homologous chromosomes exchange genes during process called “_______”

A

crossing over

40
Q

These homologous chromosomes separate during _____ of meiosis – so chromosomes in gametes are different from each other due to ________

A

2nd division; crossing over

41
Q

Crossing over increases _______ and is the reason why siblings look different

A

genetic variation

42
Q

______ – process by which an egg and sperm unite

A

Fertilization

43
Q

______ – fertilized egg

A

Zygote

44
Q

______ – organism in early stage of development

A

Embryo

45
Q
A