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Biology > Unit 8 > Flashcards

Unit 8 Flashcards

1
Q

Why do cells divide?

A
  • reproduction of cells
  • unicellular organisms can reproduce an entire organism
  • growth
  • repair
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2
Q

What are the stages and what occurs during these stages?

A

INTERPHASE

  • growth 1/growth, increase in cytoplasm
  • synthesis/ duplication of chromosomes
  • growth 2/ growth, preparation for division

MITOTIC PHASE
-division of the nucleus

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3
Q

Why must the cell cycle be controlled?

A

Because without control, cells would divide uncontrollably and produce tumors which can have serious health effects

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4
Q

What are growth factors ?

A

A protein secreted by certain body cells that stimulates other cells to divide

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5
Q

What is anchorage dependency?

A

Cells must be in contact with a solid surface to divide

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6
Q

What is density dependent inhibition?

A

A phenomenon where crowded cells stop dividing

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7
Q

Characteristics of a cancer cell

A

Divide rapidly often in the absence of growth factors

Do not divide by the rules of cell division (ex density Dependence)

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8
Q

Cell checkpoints

A

Control points where signals regulate the cell cycle

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9
Q

G1 checkpoint

A

Allows entry into the S phase or causes the cell the leave the cycle entering a non dividing g0 phase

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10
Q

What is cancer ?

A

A disease of the cell cycle when the cells do not respond normally to the cell cycle control system, these cells divide excessively and invade other tissues of the body

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11
Q

What is tumor

A

An abnormally growing mass of body cells

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12
Q

Malignant

A

Cells spread into neighboring tissues or other parts of the body and infect normal tissues

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13
Q

Benign

A

The abnormal cells stay at the original site

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14
Q

how many parents in asexual reproduction?

A

1

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15
Q

how many parents in sexual reproduction?

A

2

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16
Q

traits in asexual and sexual reproduction?

A

asexual: identical to original cell or offspring
sexual: Offspring are similar to parents, but show VARIATION in traits

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17
Q

what do unicellular organisms use cell division for?

A

to reproduce an entire organism

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18
Q

what is the cell cycle?

A

*The cell cycle is an ordered sequence of events for cell division

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19
Q

what are the two stages of the cell cycle?

A

interphase

mitotic phase

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20
Q

what stage takes up most of the cell cycle?

A

interphase

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21
Q

*What happens to the cell during interphase?

A

*Interphase:
* 90% of time
*GROWING phase
*Duplication of cell contents
•G1—growth, increase in cytoplasm
•S—duplication of chromosomes
•G2—growth, preparation for division

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22
Q

*What are the 3 sub-phases of interphase?

A

G1, S, and G2

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23
Q

Mitotic phase

A

10% of time

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24
Q

define Mitosis—

A

division of the nucleus

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25
Q

*Mitosis progresses through a series of stages (list the phases)

A
  • Prophase
  • Prometaphase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis – division of cytoplasm
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26
Q

*Mitotic spindle (spindle fibers)

A
  • composed of microtubules
  • produced by centrosomes, structures in the cytoplasm that
  • Organize microtubule arrangement
  • Contain a pair of centrioles in animal cells
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27
Q

*Cytokinesis in Animal Cells:

A

Cleavage furrow

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28
Q

*Cytokinesis in plant cells:

A

cell plate formation

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29
Q

*WHY must cell division be controlled?

A
  • allows for normal growth and development of tissue

* without control, cells can divide too much, invading normal tissues

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30
Q

What is a growth factor?

A
  • Growth factors are proteins that stimulate division
  • Different cell types respond specifically to certain growth factors
  • Cancer cells divide rapidly, often in the absence of growth factors
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31
Q

Density dependent inhibition

A

when crowded cells stop dividing

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32
Q

Anchorage dependency

A

cells must be in contact with a solid surface to divide

*In cancer cells, growth is not inhibited by other cells, and tumors form

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33
Q

What is the cell cycle control system?

A

A set of molecules (ex: growth factors) that trigger and coordinate the cell cycle

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34
Q

What are cell cycle checkpoints:

A

*Control points where signals regulate the cell cycle

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35
Q

What are the 3 major checkpoints?

A
  • G1 checkpoint allows entry into the S phase , or causes the cell to leave the cycle, entering a nondividing G0 phase (ex: nerve and muscle cells)
  • G2 checkpoint
  • M checkpoint
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36
Q

Describe what is happening at the G1 checkpoint

A
  • A growth factor binds to a receptor on the cell membrane
  • Within the cell cytoplasm, a signal transduction pathway sends the signal through a series of relay molecules
  • The signal reaches the cell cycle control system (in the nucleus) to allow cell to enter S phase (replication)
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37
Q

What is cancer?

A

*Too much cell division

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38
Q

What is a tumor?

A

An abnormal mass of body cells, due to uncontrolled cell division

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39
Q

What is the difference between benign & malignant tumors?

A
  • Benign: tumors that remain at the original site

* Malignant: tumors that spread to nearby tissue (metastasize), disrupting normal organ function

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40
Q

what do multicelular organisms use cell decision for?

A

development
growth
repair

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41
Q

Cells arise from…….

A

preexisting cells

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42
Q

where does binary fission occur

A

prokaryotic cells

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43
Q

what is dna like in prokaryotic cells

A

circular and not w/in nucleus

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44
Q

differences between eukaryotic and prokaryotic organisms?

A

Eukaryotic

  • More complex
  • Ex: human cells carry about 25,000 genes
  • DNA found in the nucleus
  • DNA in the form of chromosomes

Prokaryotic

  • Unicellular
  • Ex: typical bacterium carry only 3,000 genes
  • DNA floating in cytoplasm (no nucleus)
  • DNA in coiled/circular form
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45
Q

what type of organism has a more complex cell division?

A

eukaryotic

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46
Q

what are eukaryotic chromosomes composed of

A

chromatin

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47
Q

dna + proteins

A

chromatin

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48
Q

Highly compacted chromatin; this occurs when cell is preparing to divide.

A

chromosome

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49
Q

chromosome has two copies called _______

A

sister chromatids

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50
Q

area where 2 chromatids are

A

centromere

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51
Q

Why must cell division be controlled?

A

Allows for normal growth and development of tissue. Without control, cells can divide too much, invading normal tissues.

52
Q

Proteins that stimulate division

A

Growth factors

53
Q

When crowded cells stop dividing

A

Density dependent inhibition

54
Q

Cells must be in contact with a solid surface to divide

A

Anchorage dependency

55
Q

A set of molecules that trigger and coordinate the cell cycle

A

Cell cycle control system

56
Q

Control points where signals regulate the cell cycle

A

Cell cycle checkpoints

57
Q

Checkpoint that allows entry into the S phase

A

G1 checkpoint

58
Q

Nondividing phase

A

G0 phase

59
Q

Too much cell division

A

Cancer

60
Q

Abnormal mass of body cells, due to uncontrolled cell division

A

Tumor

61
Q

Tumors that remain at the original site

A

Benign tumor

62
Q

Tumors that spread to nearby tissue(metastasize), disrupting normal organ function

A

Malignant tumor

63
Q

Types of cancers

A

Carcinoma, sarcoma, leukemia, lymphoma

64
Q

what happens to the sister chromatids as the cell divides

A

they separate

65
Q

Once separated from its sister, each chromatid is called a

A

chromosome

66
Q

what are changes in an organisms dna

A

mutations

67
Q

what causes genetic variation?

A

a mutation arises and is reshuffled between genes

68
Q

How does the orientation of homologous chromsomes effect the gametes and lead to genetic variation?

A

There is 50/50 chance of the maternal (red) or paternal (blue) chromosome facing a given pole

69
Q

•What is a tetrad?

A

A pair of homologous chromosome

70
Q

•Where does each chromosome come from?

A

one from each parent

71
Q

Define Crossing over:

A

exchange of segments of chromosomes within a homologous pair (tetrad)

72
Q

what is a chiasma

A

the site of crossing over

73
Q

Genetic recombination:

A

production of new combinations of genes due to CROSSING OVE

74
Q

How does crossing over lead to genetic variation?

A

*One parent contributes the genes for brown coat (C) with black eyes (E)
*The other parent donates the genes for white coat (c) with pink eyes (e)
*Crossing over occurs
*Four genetically different chromosomes are produced:
•2 parental (original) versions carrying genes for brown coat with black eyes and white coat with pink eyes

75
Q

t/f errors happen in meiosis

A

true

76
Q

*What is a karyotype?

A

an ordered display of magnified images of an individual’s chromosomes arranged in pairs, starting with the longest

77
Q

how can chromosomal abnormalities be detected?

A

karyotyoe

78
Q

how is a karyotype prepaired?

A
  • Lymphocytes (white blood cells) are treated with a chemical to stimulate mitosis
  • WBCs are treated with another chemical to arrest mitosis at metaphase
  • At this stage, chromatin is condensed and each chromosome is easy to see
79
Q

how many chromosomes do humans have? how many pairs

A

46 organized to 23 pairs

80
Q

which pairs are autosomes?

A

1-22

81
Q

what number is the sex chromosome?

A

23

82
Q

female gamete?

A

XX

83
Q

male gamete?

A

XY

84
Q

what is the most common human chromosome abnormality?

A

trisomy 21

85
Q

characteristics of down syndrome?

A 
characteristic facial features 
susceptibility to disease
shortened life span 
mental retardation 
variation in charcateristics
86
Q

t/f the younger a mother is the more likely their child is to get down syndrome

A

false

the older

87
Q

how are gametes different from gametes?

A

crossing over(which leads to genetic recombination) and orientation

88
Q

homologous chromosomes

A

pairs of chromosomes that are matched in length, centromere position, gene locations

89
Q

autosomes

A

pairs of chromosomes that have the same size and the same genes; 22 pairs of chromosomes that are not sex chromosomes

90
Q

sex chromosomes

A

the x and y chromosomes that determine an individual’s sex

91
Q

diploid

A

cells that have 2 homologous sets of chromosomes(2n and somatic)

92
Q

hapoid cells

A

cells that have 1 set of chromosomes (half the # of chromosomes) (n) (gametes - sperm and egg)

93
Q

diploid and haploid number for humans

A

diploid- 46 chromosomes

haploid- 23 chromosomes

94
Q

how does mitosis fit into the life cycle?

A

the zygote can develop into a multicellular adult

95
Q

how does meiosis fit into the lift cycle

A

it creates gametes: eggs in females, sperm in males

96
Q

how are the stages of meiosis 1 different from meiosis 2?

A

there are 2 pairs of homologous chromosomes starting in meiosis 1, and 1 pair in meiosis 2.
meiosis 1 splits one cell into 2, meiosis 2 splits 2 cells into 4.
meiosis 1 is 2n=46, meiosis 2 results in n= 23

97
Q

what are the chromosomes doing in each stage of meiosis?

A

p1- 2 pairs of homologous chromosomes
m1- homologous chromosomes line up at the middle , creating tetrads
a1- chromatids are pulled apart
t1- total split into 2 cells, no duplication
p2- 2 separate cells w 2 chromosomes
m2- chromosomes are lined up
a2- chromatids are pulled apart
t2- split into 4 cells w 2 separate chromatids

98
Q

similarities btw mitosis and meiosis

A

one duplication of chromosomes

99
Q

differences btw meiosis and mitosis

A

mitosis : 2 genetically identical cells w the same # of chromosomes as the original
meiosis : 4 genetically different cells w 1/2 the chromosome # as the original

100
Q

What are the 2 types of cell division?

A

Mitosis and Meiosis

101
Q

What are the major differences between asexual and sexual reproduction?

A

Asexual - genetically identical offspring from one parent without the participation of sperm and egg
Sexual - resemble parents but not identical, offspring inherits a unique combination of genes, two parents, participation of cell and egg

102
Q

Why does cell division occur in unicellular organisms?

A

To reproduce an entire organism

103
Q

Why does cell division occur in multicellular organisms?

A

To reproduce asexually (such as plants grow from cuttings)

104
Q

What is binary fission?

A

A type of cell division/means of asexual reproduction in which a parent organism, often a single cell, divides into 2 individuals of about equal size

105
Q

How does binary fission occur?

A
  1. Duplicating of chromosome and separation of copies
  2. Continued elongation of the cell and movement of copies
  3. Division into 2 daughter cells
106
Q

What are the major differences between eukaryotic and prokaryotic cell division?

A

Eukaryotic - all chromosomes duplicate before the cell divides
Prokaryotic - does not duplicate before dividing

107
Q

What is chromatin?

A

Complex of DNA and proteins that constitutes eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when a cell is not dividing

108
Q

What is a chromosome?

A

A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis

109
Q

What is a chromatid?

A

Half of a chromosome, have identical DNA/genetic material

110
Q

What is a centromere?

A

Between sister chromatids, hold them together

111
Q

An occasional mishap in which the members of a chromosome pair fail to separate.

A

Nondisjunction

112
Q

Nondisjunction in Meiosis I: A pair of homologous chromosomes does not separate, resulting in gametes ending up with abnormal numbers of chromosomes: two gametes have three, the other two have only one each.
Nondisjunction in Meiosis II: One pair of sister chromatids fails to move apart, resulting in two abnormal gametes and two normal gametes.

A

The differences between nondisjunction in Meiosis I and II

113
Q

If a fragment of a chromosome is lost, the remaining chromosome will have this

A

Deletion

114
Q

If a fragment from one chromosome joins to a sister chromatid or homologous chromosome, it will produce this

A

Duplication

115
Q

If a fragment reattaches to the original chromosome but in the reverse direction, this results

A

Inversion

116
Q

The attachment of a chromosomal fragment to a nonhomologous chromosome

A

Translocation

117
Q

what is mitosis

A

the division of a single nucleus 2 genetically identical daughter nuclei. part of mitotic phase

118
Q

what is cytokinesis

A

the division of the cytoplasm into 2 separate daughter cells. occurs during telophase and is part of the mitotic phase

119
Q

what are the stages of mitosis? what are the chromosomes doing during each?

A

interphase- chromosomes are duplicated
prophase- chromosomes become discrete due to chromatin fibers becoming more tightly coiled and folded
prometaphase- chromosomes are highly condensed and attached to spindles
metaphase- chromosomes align in middle
annaphase- chromosomes come apart and split sister chromatids
telophase- chromatin of chromosomes uncoils
cytokinesis- chromosomes in different cells

120
Q

how do plant and animal cells differ in cytokinesis?

A

animal cells- involved cleavage furrow which pinches the cell in 2
plant cells- forms a cell plate that grows outward and eventually becomes part of plasma membrane and cell wall

121
Q

how does independent orientation of chromosomes provide variation in gametes?

A

there is a 50% chance that a particular daughter cell will get the maternal chromosome of a certain homologous pair and a 50% chance it will receive the paternal chromosome.

122
Q

how does crossing over provide variation in gametes?

A

crossing over creates recombinant chromosomes having a combination of genes that were originally different, though homologous chromosomes

123
Q

what is a karyotype?

A

karyotype- ordered display of magnified images of an individual’s chromosomes arranged in pairs, starting with the longest

124
Q

what information does a karyotype give you?

A

it can show errors that occurred in meiosis that lead gametes to containing chromosomes in abnormal numbers or with major alterations in structure. it can show things such as trisomy 21

125
Q

what is trisomy 21? how does it occur?

A

trisomy 21 is when one has 3 #21 chromosomes and has 47 chromosomes. it is known as Down Syndrome. it occurs due to nondisjunction, when the members of chromosomes fail to separate

126
Q

How are types of cancers categorized & what are some of these categories?

A
  • Based on their site of origin

* EX: carcinoma, sarcoma, leukemia, lymphoma

Biology (7 decks)

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