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Bio ch 8 Flashcards

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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
what happens during the mitotic phase
the actual cell division
26
what are the three subphases of interphase
G1 (first gap), S phase, and G2 (second gap)
27
what happens in the G1 stage of interphase
the cell grows
28
what happens in the S phase of interphase
Cell continues to grow | Chromosomes are duplicated; S stands for synthesis of DNA (DNA replication
29
what happens in the G2 stage of interphase
cell grows more as it completes preparations for cell divisions
30
what are the two phases of the mitotic phase
mitosis | cytokinesis
31
what happens during mitosis
Nucleus and its contents (most importantly the duplicated chromosomes) divide and are evenly distributed, forming two daughter nuclei
32
what happens during cytokinesis
Cytoplasm is divided into two
33
what are the phases of mitosis
``` prophase prometaphase metaphase anaphase telophase and cytokinesis ```
34
what happens during prophase
nucleoli disappears chromatin forms sister chromatids with centromeres mitotic spindle forms centromeres move away from each other
35
what happens during prometaphase
nuclear membrane breaks down spindle microtubules connect to kinetochores on the chromatids chromosomes move towards the middle
36
what happens during metaphase
chromosomes lie in the metaphase plate | mitotic spindle is fully formed
37
what happens during anaphase
centromeres come apart and chromatids are separated and pulled toward opposite ends of the cell daughter chromosomes have formed cell is elongated
38
what happens during telophase
``` cell continues to elongate daughter nuclei and nucleoli appear chromosomes uncoil mitotic spindle disappears division is complete ```
39
what happens during cytokinesis
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)
40
why is cytokinesis different for plant and animal cells
bc plant cells have a cell wall and animal cells don't
41
what controls cell division
anchorage dependence density dependence growth factors
42
what is a growth factor
a protein secreted by certain body cells that stimulates other cells to divide
43
what is an example of a growth factor
VEGF
44
what is a density dependent inhibition
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
45
what is one difference between cancer cells and normal cells
cancer cells don't exhibit density-dependent inhibition
46
what is anchorage dependence
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
what is the cell cycle control system
a cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle
48
explain how the cell cycle control system is not like a row of falling dominoes
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
what is a checkpoint in the cell cycle
a critical control point where stop and go-ahead signals can regulate the cycle
50
where are the 3 major checkpoints in the cell cycle
in the G1 and G2 sub phases of interphase and in the M phase
51
what is the Gzero phase
a permanently non-dividing state; mature nerve cells and muscle cells are in the Gzero phase
52
explain how a growth factor might affect the cell cycle control system
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
what is a signal transduction pathway
a series of protein molecules that conveys a message
54
what is apoptosis
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
what is cancer
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
what is a tumor
an abnormally growing mass of body cells
57
what is a benign tumor
generally harmless; the lump that results if the abnormal cells remain at the original site; often can be completely removed by surgery
58
what is a malignant tumor
harmful; can spread into neighboring tissues and other parts of the body, displacing normal tissue and interrupting organ function as it goes
59
what is metastasis
the spread of cancer cells beyond their original site
60
what are 2 ways cancer can metastasize
cancer cells may separate from the original tumor or secret signal molecules that cause blood vessels to grow towards the tumor
61
what are carcinomas
cancers that originate in the external or internal coverings of the body; ex: skin or lining of intestine
62
what are sarcomas
cancers that arise in tissues that support the body; ex: muscle or bone
63
what are leukemias and lymphomas
cancers of blood-forming tissues; ex: bone marrow, spleen, and lymph nodes
64
what are some things that differentiate cancer cells from normal cells
- 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
what are some treatments for cancer
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
what are homologous chromosomes
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
what is a diploid cell
any cell with 2 homologous sets of chromosomes (2n); somatic cell
68
what is a haploid cell
any cell with one set of chromosomes (n); sex cells
69
what are sex chromosomes
determine sex; XX or XY
70
what are gametes
egg and sperm cells
71
what happens in fertilization
a haploid sperm cell from the father fuses with a haploid egg cell from the mother
72
what is a zygote
a fertilized egg
73
why are our gametes haploid
to prevent the number of chromosomes from doubling in every generation
74
what is meiosis
a type of cell division that produces haploid gametes in diploid organisms
75
what are the phases of meiosis
``` Interphase Prophase I Metaphase I Anaphase I Telophase I/Cytokinesis Prophase II Metaphase II Anaphase II Telophase II/Cytokinesis ```
76
what happens during interphase of meiosis
the chromosomes and centrosomes duplicate
77
what happens during Prophase I
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
what happens during metaphase I
tetrads line up at metaphase plate | spindle fibers attach to centromere of each homologous chromosome
79
what happens during anaphase I
homologous chromosomes separate but sister chromatids remain attached
80
what happens during telophase I/cytokinesis
chromosomes arrive at the poles of the cells; each chromosome still consists of two sister chromatids 2 haploid daughter cells have formed
81
what happens during prophase II
a spindle forms and moves the chromosomes towards the middle of the cell
82
what happens during metaphase II
chromosomes are aligned on metaphase plate
83
what happens during anaphase II
sister chromatids separate and move toward opposite ends of the cell
84
what happens in telophase II
nuclei form at cell poles and cytokinesis occurs at the same time there are now 4 daughter haploid cells
85
how are meiosis and mitosis different
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
how are meiosis and mitosis the same
chromosomes duplicate only once, during the S phase of interphase
87
what leads to genetic variations in offspring
- 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
what is the total number of combinations of chromosomes that meiosis can package into gametes
2^n where n is the haploid number
89
how many combinations of chromosomes are there when a gamete from one person unites with a gamete from another person in fertilization
64 trillion
90
how many possible chromosome combinations are there that meiosis can create in humans
8 million
91
what is crossing over
an exchange of corresponding segments between non-sister chromatids of homologous chromosomes
92
what does crossing over do
produces hybrid chromosomes with new combinations of maternal and paternal genes
93
what is a karyotype
an ordered display of magnified images of an individual's chromosomes arranged in pairs
94
how do you prepare a karyotype from a blood sample
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
what is it called when there are 3 number 21 chromosomes
trisomy 21, or Down Syndrome
96
how do the chances of having a child with down syndrome relate to the age of the mom
directly proportional
97
what is nondisjunction
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
what causes down syndrome
nondisjunction
99
what is it called when males have an extra X chromosome (XXY)
kleinfelter syndrome symptoms: Have male sex organs, normal intelligence, abnormally small testes, are sterile, and has female body characteristics
100
what is it called when females only have one X chromosome (XO)
turner syndrome symptoms: Short, have web of skin extending between the neck and shoulders, are sterile, poor development of breasts, normal intelligence
101
what happens when males have an extra Y chromosome (XY)
No well defined symptoms, tend to be taller than avg
102
what happens when women have an extra x chromosome (XXX)
Cannot be distinguished from XX females except by karyotype
103
how could a diploid plant become a polyploid plant
if the gametes are accidentally produced by mitosis, it will produce a tetraploid (4n) plant
104
what are some polyploid plants
wheat, potatoes, apples, and corn
105
what are the 4 alterations of chromosome structure
deletion duplication inversion translocation
106
what is a deletion
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
what is a duplication
if a fragment from one chromosome joins to a sister chromatid or homologous chromosome
108
what is an inversion
if a fragment reattaches to the original chromosome but in the reverse orientation
109
why are inversions less likely than duplications or deletions to produce harmful effects
bc in inversions all genes are present in their normal number
110
what is a translocation
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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