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Bio ch 8 Flashcards

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Biology 101 flashcards
1
Q

what is meant by “like begets like”

A

only maple trees produce more maple trees, only dogs produce more dogs, etc

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2
Q

what is it called when a cell undergoes reproduction

A

cell division

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3
Q

describe the genetics of the two daughter cells that result from a parent cell that undergoes cell division

A

the 2 daughter cells are genetically identical to each other and the original parent cell

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4
Q

what happens to the chromosomes in a cell before the cell divides

A

they are duplicated by the cell

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5
Q

what happens to the duplicated chromosomes in a cell during the division process

A

one set is distributed to each daughter cell; each receives identical sets of chromosomes from the parent cell, making each offspring cell genetically identical to the other and to the parent cell

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6
Q

what is asexual reproduction

A

the creation of genetically identical offspring by a single parent without the participation of sperm and egg

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7
Q

what is the main principle of asexual reproduction

A

the lone parent and each of its offspring have identical genes

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8
Q

what is sexual reproduction

A

requires fertilization of an egg by a sperm; can produce great variation among offspring

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9
Q

describe the offspring of sexual reproduction

A

not genetically identical to their parents or to each other

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10
Q

compare asexual and sexual reproduction

A

asexual: single parent, genetically identical offspring
sexual: requires fertilization of sperm and egg, genetically unique offspring

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11
Q

how do prokaryotes reproduce

A

binary fission

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12
Q

describe the process of binary fission

A
  1. as the chromosome inside the prokaryote is duplicating, the copies move towards opposite ends of the cell
  2. the cell elongates
  3. when the chromosome duplication is complete and the cell has almost doubled in size, the plasma membrane grows inward and more cell wall is made, dividing the parent cell into genetically identical 2 daughter cells.
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13
Q

what is chromatin

A

DNA in the form of a diffuse mass of long, thin fibers composed of roughly equal amounts of DNA and protein molecules; not visible under a light microscope

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14
Q

what happens to a cell’s chromatin as it prepares to divide

A

its chromatin coils up, forming tight, distinct chromosomes that are visible under a light microscope

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15
Q

what is budding

A

a form of asexual reproduction in which a new organism develops from an outgrowth or bud (polyp) due to cell division at one particular site. The new organism remains attached as it grows, separating from the parent organism only when it is mature, leaving behind scar tissue.

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16
Q

what is fragmentation

A

a form of asexual reproduction or cloning in which an organism is split into fragments. Each of these fragments develop into mature, fully grown individuals that are clones of the original organism.

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17
Q

what is parthenogenesis

A

a type of asexual reproduction in which a cell fertilized the egg but it wasn’t a cell from a male; may be clones of the mother, haploid, or diploid

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18
Q

what is vegetative propagation

A

a form of asexual reproduction of a plant. plant tissues and organs are regenerated from another part of the plant and a new organism can be produced

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19
Q

how is chromatin different from chromosomes

A

less condensed, cant be seen with a light microscope, composed of roughly equal amounts of DNA and protein molecules (chromosomes have more proteins to to help maintain structure and control activity of its genes

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20
Q

explain the process of cell reproduction in eukaryotes

A
  1. chromosomes are duplicated before they condense and the cell divides
  2. the DNA molecule of each chromosome is replicated and new protein molecules attach as needed. each chromosome now consists of two copies called sister chromatids, which contain identical copies of the DNA molecule
  3. the 2 sister chromatids are joined together especially tightly at a narrow waist called the centromere
  4. when the cell divides, the nucleus and the cytoplasm also divide, and the sister chromatids of a duplicated chromosome separate from each other. Once separated it is called a chromosome and it is identical to the parent chromosome
  5. each of the new chromosomes goes to one of the daughter cells. Each daughter cell receives a complete and identical set of chromosomes
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21
Q

why is cell division important

A

it is the basis of reproduction for every organism
enables multicellular organisms to grow to adult size
replaces worn-out or damaged cells

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22
Q

what are the 2 main stages of the cell cycle

A

interphase

mitotic phase

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23
Q

what is the cell cycle

A

an ordered sequence of events that extends from the time a cell is first formed from a dividing parent cell until its own division into two cells

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24
Q

what happens during interphase

A

the cell roughly doubles everything in its cytoplasm and precisely replicates its chromosomal DNA; increases its supply of nutrients; nuclear envelope exists; 2 centrosomes have formed, each with two centrioles

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25
Q

what happens during the mitotic phase

A

the actual cell division

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26
Q

what are the three subphases of interphase

A

G1 (first gap), S phase, and G2 (second gap)

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27
Q

what happens in the G1 stage of interphase

A

the cell grows

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28
Q

what happens in the S phase of interphase

A

Cell continues to grow

Chromosomes are duplicated; S stands for synthesis of DNA (DNA replication

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29
Q

what happens in the G2 stage of interphase

A

cell grows more as it completes preparations for cell divisions

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30
Q

what are the two phases of the mitotic phase

A

mitosis

cytokinesis

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31
Q

what happens during mitosis

A

Nucleus and its contents (most importantly the duplicated chromosomes) divide and are evenly distributed, forming two daughter nuclei

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32
Q

what happens during cytokinesis

A

Cytoplasm is divided into two

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33
Q

what are the phases of mitosis

A 
prophase
prometaphase
metaphase
anaphase
telophase and cytokinesis
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34
Q

what happens during prophase

A

nucleoli disappears
chromatin forms sister chromatids with centromeres
mitotic spindle forms
centromeres move away from each other

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35
Q

what happens during prometaphase

A

nuclear membrane breaks down
spindle microtubules connect to kinetochores on the chromatids
chromosomes move towards the middle

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36
Q

what happens during metaphase

A

chromosomes lie in the metaphase plate

mitotic spindle is fully formed

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37
Q

what happens during anaphase

A

centromeres come apart and chromatids are separated and pulled toward opposite ends of the cell
daughter chromosomes have formed
cell is elongated

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38
Q

what happens during telophase

A 
cell continues to elongate
daughter nuclei and nucleoli appear
chromosomes uncoil
mitotic spindle disappears
division is complete
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39
Q

what happens during cytokinesis

A

Division of cytoplasm
separation into two daughter cells
animal cells - cleave furrow (cel pinches in two)
plant cells - cell plate (vesicles containing cell wall material join to form a cell plate which grows outward to join the parent cell wall)

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40
Q

why is cytokinesis different for plant and animal cells

A

bc plant cells have a cell wall and animal cells don’t

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41
Q

what controls cell division

A

anchorage dependence
density dependence
growth factors

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42
Q

what is a growth factor

A

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

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43
Q

what is an example of a growth factor

A

VEGF

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44
Q

what is a density dependent inhibition

A

a phenomenon in which crowded cells stop dividing
ex: animal cells on the surface of a dish multiply to form a single layer and usually stop dividing when they fill the space and touch one another; the physical contact of cell surface proteins between adjacent cells is responsible for inhibiting cell division

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45
Q

what is one difference between cancer cells and normal cells

A

cancer cells don’t exhibit density-dependent inhibition

46
Q

what is anchorage dependence

A

they must be in contact with a sold surface, such as the inside of a culture dish or the extracellular matrix of a tissue, to divide

47
Q

what is the cell cycle control system

A

a cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle

48
Q

explain how the cell cycle control system is not like a row of falling dominoes

A

for example, in the M phase, metaphase does not automatically lead to anaphase. Instead, proteins of the cell cycle control system must trigger the separation of sister chromatids that marks the start of anaphase

49
Q

what is a checkpoint in the cell cycle

A

a critical control point where stop and go-ahead signals can regulate the cycle

50
Q

where are the 3 major checkpoints in the cell cycle

A

in the G1 and G2 sub phases of interphase and in the M phase

51
Q

what is the Gzero phase

A

a permanently non-dividing state; mature nerve cells and muscle cells are in the Gzero phase

52
Q

explain how a growth factor might affect the cell cycle control system

A

A cell that responds to a growth factor has molecules of a specific receptor protein in its plasma membrane. Binding of the growth factor to the receptor triggers a signal transduction pathway in the cell. This conveys a message to the cell that leads to cell division. The “signals” are changes that each protein molecule induces in the next molecule in the pathway. Via a series of relay proteins, a signal finally reaches the cell cycle control system and overrides the breaks that otherwise prevent progress of the cell cycle.

53
Q

what is a signal transduction pathway

A

a series of protein molecules that conveys a message

54
Q

what is apoptosis

A

programmed cell death; the cell goes through a series of steps to shut down; The cytoskeleton collapses, the nuclear envelope disassembles, and the nuclear DNA breaks up into fragments; a way to keep the amount of cells constant

55
Q

what is cancer

A

cells that do not respond to the cell control system and divide excessively; an individual with a malignant tumor is said the have cancer

56
Q

what is a tumor

A

an abnormally growing mass of body cells

57
Q

what is a benign tumor

A

generally harmless; the lump that results if the abnormal cells remain at the original site; often can be completely removed by surgery

58
Q

what is a malignant tumor

A

harmful; can spread into neighboring tissues and other parts of the body, displacing normal tissue and interrupting organ function as it goes

59
Q

what is metastasis

A

the spread of cancer cells beyond their original site

60
Q

what are 2 ways cancer can metastasize

A

cancer cells may separate from the original tumor or secret signal molecules that cause blood vessels to grow towards the tumor

61
Q

what are carcinomas

A

cancers that originate in the external or internal coverings of the body; ex: skin or lining of intestine

62
Q

what are sarcomas

A

cancers that arise in tissues that support the body; ex: muscle or bone

63
Q

what are leukemias and lymphomas

A

cancers of blood-forming tissues; ex: bone marrow, spleen, and lymph nodes

64
Q

what are some things that differentiate cancer cells from normal cells

A
  • do not heed normal signals that regulate the cell cycle
  • come cancer cells make growth signals and divide continuously
  • if they do stop dividing, they do so at random points in the cell cycle
  • cancer cells are immortal and can go on dividing indefinitely
65
Q

what are some treatments for cancer

A

surgery (used for localized tumors)
radiation (but this is high energy and damages normal body cells as well)
chemotherapy (used to treat widespread or metastatic tumors)

66
Q

what are homologous chromosomes

A

a pair of chromosomes (one from each parent); both carry genes controlling the same inherited characteristics in the same places (they may still have different versions of the same gene)

67
Q

what is a diploid cell

A

any cell with 2 homologous sets of chromosomes (2n); somatic cell

68
Q

what is a haploid cell

A

any cell with one set of chromosomes (n); sex cells

69
Q

what are sex chromosomes

A

determine sex; XX or XY

70
Q

what are gametes

A

egg and sperm cells

71
Q

what happens in fertilization

A

a haploid sperm cell from the father fuses with a haploid egg cell from the mother

72
Q

what is a zygote

A

a fertilized egg

73
Q

why are our gametes haploid

A

to prevent the number of chromosomes from doubling in every generation

74
Q

what is meiosis

A

a type of cell division that produces haploid gametes in diploid organisms

75
Q

what are the phases of meiosis

A 
Interphase
Prophase I
Metaphase I
Anaphase I
Telophase I/Cytokinesis
Prophase II
Metaphase II
Anaphase II
Telophase II/Cytokinesis
76
Q

what happens during interphase of meiosis

A

the chromosomes and centrosomes duplicate

77
Q

what happens during Prophase I

A

Chromatin coils up and individual chromosomes become visible
homologous chromosomes (each composed of 2 sister chromatids) come together as pairs (process called synapsis); the resulting structure of 4 chromatids is called a tetrad
crossing over occurs; exchange of genetic info
mitotic spindle begins to form
nuclear envelope breaks into fragments
chromosome tetrads move toward center of cell

78
Q

what happens during metaphase I

A

tetrads line up at metaphase plate

spindle fibers attach to centromere of each homologous chromosome

79
Q

what happens during anaphase I

A

homologous chromosomes separate but sister chromatids remain attached

80
Q

what happens during telophase I/cytokinesis

A

chromosomes arrive at the poles of the cells; each chromosome still consists of two sister chromatids
2 haploid daughter cells have formed

81
Q

what happens during prophase II

A

a spindle forms and moves the chromosomes towards the middle of the cell

82
Q

what happens during metaphase II

A

chromosomes are aligned on metaphase plate

83
Q

what happens during anaphase II

A

sister chromatids separate and move toward opposite ends of the cell

84
Q

what happens in telophase II

A

nuclei form at cell poles and cytokinesis occurs at the same time
there are now 4 daughter haploid cells

85
Q

how are meiosis and mitosis different

A

mitosis:
- provides for growth, tissue repair, and asexual reproduction
- produces 2 genetically identical diploid daughter cells
- involves one division of the nucleus
Meiosis:
- needed for sexual reproduction
- produces 4 genetically unique haploid daughter cells
- involves 2 nuclear and cytoplasmic divisions

86
Q

how are meiosis and mitosis the same

A

chromosomes duplicate only once, during the S phase of interphase

87
Q

what leads to genetic variations in offspring

A
  • the alignment of the tetrads at metaphase one; they orient independently and there are many possible arrangements
  • random nature of fertilization
  • the fact that homologous chromosomes can bear 2 different kinds of genetic information for the same characteristic
  • crossing over
88
Q

what is the total number of combinations of chromosomes that meiosis can package into gametes

A

2^n where n is the haploid number

89
Q

how many combinations of chromosomes are there when a gamete from one person unites with a gamete from another person in fertilization

A

64 trillion

90
Q

how many possible chromosome combinations are there that meiosis can create in humans

A

8 million

91
Q

what is crossing over

A

an exchange of corresponding segments between non-sister chromatids of homologous chromosomes

92
Q

what does crossing over do

A

produces hybrid chromosomes with new combinations of maternal and paternal genes

93
Q

what is a karyotype

A

an ordered display of magnified images of an individual’s chromosomes arranged in pairs

94
Q

how do you prepare a karyotype from a blood sample

A

A blood sample is treated with a chemical that stimulates mitosis
Grown in culture for several days
Treated with another chemical to stop mitosis at metaphase

95
Q

what is it called when there are 3 number 21 chromosomes

A

trisomy 21, or Down Syndrome

96
Q

how do the chances of having a child with down syndrome relate to the age of the mom

A

directly proportional

97
Q

what is nondisjunction

A

when a pair of homologous chromosomes fails to separate in meiosis I or a pair of sister chromatids fails to separate in meiosis II, which creates an abnormal amount of chromosomes in some or all of the gametes

98
Q

what causes down syndrome

A

nondisjunction

99
Q

what is it called when males have an extra X chromosome (XXY)

A

kleinfelter syndrome
symptoms: Have male sex organs, normal intelligence, abnormally small testes, are sterile, and has female body characteristics

100
Q

what is it called when females only have one X chromosome (XO)

A

turner syndrome
symptoms: Short, have web of skin extending between the neck and shoulders, are sterile, poor development of breasts, normal intelligence

101
Q

what happens when males have an extra Y chromosome (XY)

A

No well defined symptoms, tend to be taller than avg

102
Q

what happens when women have an extra x chromosome (XXX)

A

Cannot be distinguished from XX females except by karyotype

103
Q

how could a diploid plant become a polyploid plant

A

if the gametes are accidentally produced by mitosis, it will produce a tetraploid (4n) plant

104
Q

what are some polyploid plants

A

wheat, potatoes, apples, and corn

105
Q

what are the 4 alterations of chromosome structure

A

deletion
duplication
inversion
translocation

106
Q

what is a deletion

A

if a fragment of a chromosome is lost, the remaining chromosome will have a deletion (ex: cri du chat syndrome is the result of a deletion)

107
Q

what is a duplication

A

if a fragment from one chromosome joins to a sister chromatid or homologous chromosome

108
Q

what is an inversion

A

if a fragment reattaches to the original chromosome but in the reverse orientation

109
Q

why are inversions less likely than duplications or deletions to produce harmful effects

A

bc in inversions all genes are present in their normal number

110
Q

what is a translocation

A

attachment of a chromosomal fragment to a nonhomologous chromosome; may be reciprocal - 2 homologous chromosomes may switch segments; translocation in somatic cells may cause cancer

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