Unit 8 Flashcards
1
Q
Why do cells divide?
A
- reproduction of cells
- unicellular organisms can reproduce an entire organism
- growth
- repair
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
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
4
Q
What are growth factors ?
A
A protein secreted by certain body cells that stimulates other cells to divide
5
Q
What is anchorage dependency?
A
Cells must be in contact with a solid surface to divide
6
Q
What is density dependent inhibition?
A
A phenomenon where crowded cells stop dividing
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)
8
Q
Cell checkpoints
A
Control points where signals regulate the cell cycle
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
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
11
Q
What is tumor
A
An abnormally growing mass of body cells
12
Q
Malignant
A
Cells spread into neighboring tissues or other parts of the body and infect normal tissues
13
Q
Benign
A
The abnormal cells stay at the original site
14
Q
how many parents in asexual reproduction?
A
1
15
Q
how many parents in sexual reproduction?
A
2
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
17
Q
what do unicellular organisms use cell division for?
A
to reproduce an entire organism
18
Q
what is the cell cycle?
A
*The cell cycle is an ordered sequence of events for cell division
19
Q
what are the two stages of the cell cycle?
A
interphase
mitotic phase
20
Q
what stage takes up most of the cell cycle?
A
interphase
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
22
Q
*What are the 3 sub-phases of interphase?
A
G1, S, and G2
23
Q
Mitotic phase
A
10% of time
24
Q
define Mitosis—
A
division of the nucleus
25
*Mitosis progresses through a series of stages (list the phases)
* Prophase
* Prometaphase
* Metaphase
* Anaphase
* Telophase
* Cytokinesis – division of cytoplasm
26
*Mitotic spindle (spindle fibers)
* composed of microtubules
* produced by centrosomes, structures in the cytoplasm that
* Organize microtubule arrangement
* Contain a pair of centrioles in animal cells
27
*Cytokinesis in Animal Cells:
Cleavage furrow
28
*Cytokinesis in plant cells:
cell plate formation
29
*WHY must cell division be controlled?
* allows for normal growth and development of tissue
| * without control, cells can divide too much, invading normal tissues
30
What is a growth factor?
* 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
31
Density dependent inhibition
when crowded cells stop dividing
32
Anchorage dependency
cells must be in contact with a solid surface to divide
| *In cancer cells, growth is not inhibited by other cells, and tumors form
33
What is the cell cycle control system?
A set of molecules (ex: growth factors) that trigger and coordinate the cell cycle
34
What are cell cycle checkpoints:
*Control points where signals regulate the cell cycle
35
What are the 3 major checkpoints?
* 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
36
Describe what is happening at the G1 checkpoint
* 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)
37
What is cancer?
*Too much cell division
38
What is a tumor?
An abnormal mass of body cells, due to uncontrolled cell division
39
What is the difference between benign & malignant tumors?
* Benign: tumors that remain at the original site
| * Malignant: tumors that spread to nearby tissue (metastasize), disrupting normal organ function
40
what do multicelular organisms use cell decision for?
development
growth
repair
41
Cells arise from.......
preexisting cells
42
where does binary fission occur
prokaryotic cells
43
what is dna like in prokaryotic cells
circular and not w/in nucleus
44
differences between eukaryotic and prokaryotic organisms?
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
45
what type of organism has a more complex cell division?
eukaryotic
46
what are eukaryotic chromosomes composed of
chromatin
47
dna + proteins
chromatin
48
Highly compacted chromatin; this occurs when cell is preparing to divide.
chromosome
49
chromosome has two copies called _______
sister chromatids
50
area where 2 chromatids are
centromere
51
Why must cell division be controlled?
Allows for normal growth and development of tissue. Without control, cells can divide too much, invading normal tissues.
52
Proteins that stimulate division
Growth factors
53
When crowded cells stop dividing
Density dependent inhibition
54
Cells must be in contact with a solid surface to divide
Anchorage dependency
55
A set of molecules that trigger and coordinate the cell cycle
Cell cycle control system
56
Control points where signals regulate the cell cycle
Cell cycle checkpoints
57
Checkpoint that allows entry into the S phase
G1 checkpoint
58
Nondividing phase
G0 phase
59
Too much cell division
Cancer
60
Abnormal mass of body cells, due to uncontrolled cell division
Tumor
61
Tumors that remain at the original site
Benign tumor
62
Tumors that spread to nearby tissue(metastasize), disrupting normal organ function
Malignant tumor
63
Types of cancers
Carcinoma, sarcoma, leukemia, lymphoma
64
what happens to the sister chromatids as the cell divides
they separate
65
Once separated from its sister, each chromatid is called a
chromosome
66
what are changes in an organisms dna
mutations
67
what causes genetic variation?
a mutation arises and is reshuffled between genes
68
How does the orientation of homologous chromsomes effect the gametes and lead to genetic variation?
There is 50/50 chance of the maternal (red) or paternal (blue) chromosome facing a given pole
69
•What is a tetrad?
A pair of homologous chromosome
70
•Where does each chromosome come from?
one from each parent
71
Define Crossing over:
exchange of segments of chromosomes within a homologous pair (tetrad)
72
what is a chiasma
the site of crossing over
73
Genetic recombination:
production of new combinations of genes due to CROSSING OVE
74
How does crossing over lead to genetic variation?
*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
t/f errors happen in meiosis
true
76
*What is a karyotype?
an ordered display of magnified images of an individual’s chromosomes arranged in pairs, starting with the longest
77
how can chromosomal abnormalities be detected?
karyotyoe
78
how is a karyotype prepaired?
* 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
how many chromosomes do humans have? how many pairs
46 organized to 23 pairs
80
which pairs are autosomes?
1-22
81
what number is the sex chromosome?
23
82
female gamete?
XX
83
male gamete?
XY
84
what is the most common human chromosome abnormality?
trisomy 21
85
characteristics of down syndrome?
```
characteristic facial features
susceptibility to disease
shortened life span
mental retardation
variation in charcateristics
```
86
t/f the younger a mother is the more likely their child is to get down syndrome
false
| the older
87
how are gametes different from gametes?
crossing over(which leads to genetic recombination) and orientation
88
homologous chromosomes
pairs of chromosomes that are matched in length, centromere position, gene locations
89
autosomes
pairs of chromosomes that have the same size and the same genes; 22 pairs of chromosomes that are not sex chromosomes
90
sex chromosomes
the x and y chromosomes that determine an individual's sex
91
diploid
cells that have 2 homologous sets of chromosomes(2n and somatic)
92
hapoid cells
cells that have 1 set of chromosomes (half the # of chromosomes) (n) (gametes - sperm and egg)
93
diploid and haploid number for humans
diploid- 46 chromosomes
| haploid- 23 chromosomes
94
how does mitosis fit into the life cycle?
the zygote can develop into a multicellular adult
95
how does meiosis fit into the lift cycle
it creates gametes: eggs in females, sperm in males
96
how are the stages of meiosis 1 different from meiosis 2?
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
what are the chromosomes doing in each stage of meiosis?
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
similarities btw mitosis and meiosis
one duplication of chromosomes
99
differences btw meiosis and mitosis
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
What are the 2 types of cell division?
Mitosis and Meiosis
101
What are the major differences between asexual and sexual reproduction?
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
Why does cell division occur in unicellular organisms?
To reproduce an entire organism
103
Why does cell division occur in multicellular organisms?
To reproduce asexually (such as plants grow from cuttings)
104
What is binary fission?
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
How does binary fission occur?
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
What are the major differences between eukaryotic and prokaryotic cell division?
Eukaryotic - all chromosomes duplicate before the cell divides
Prokaryotic - does not duplicate before dividing
107
What is chromatin?
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
What is a chromosome?
A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis
109
What is a chromatid?
Half of a chromosome, have identical DNA/genetic material
110
What is a centromere?
Between sister chromatids, hold them together
111
An occasional mishap in which the members of a chromosome pair fail to separate.
Nondisjunction
112
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.
The differences between nondisjunction in Meiosis I and II
113
If a fragment of a chromosome is lost, the remaining chromosome will have this
Deletion
114
If a fragment from one chromosome joins to a sister chromatid or homologous chromosome, it will produce this
Duplication
115
If a fragment reattaches to the original chromosome but in the reverse direction, this results
Inversion
116
The attachment of a chromosomal fragment to a nonhomologous chromosome
Translocation
117
what is mitosis
the division of a single nucleus 2 genetically identical daughter nuclei. part of mitotic phase
118
what is cytokinesis
the division of the cytoplasm into 2 separate daughter cells. occurs during telophase and is part of the mitotic phase
119
what are the stages of mitosis? what are the chromosomes doing during each?
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
how do plant and animal cells differ in cytokinesis?
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
how does independent orientation of chromosomes provide variation in gametes?
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
how does crossing over provide variation in gametes?
crossing over creates recombinant chromosomes having a combination of genes that were originally different, though homologous chromosomes
123
what is a karyotype?
karyotype- ordered display of magnified images of an individual's chromosomes arranged in pairs, starting with the longest
124
what information does a karyotype give you?
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
what is trisomy 21? how does it occur?
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
How are types of cancers categorized & what are some of these categories?
* Based on their site of origin
| * EX: carcinoma, sarcoma, leukemia, lymphoma
