Chapter 8 Flashcards
Cell Division & Reproduction
1
Q
cell division
A
cell reproduction;
- genome duplication / cytoplasm division
- makes 2 genetically identical daughter cells
2
Q
chromosomes
A
gene structure in nucleus
- long DNA molecule and proteins
3
Q
asexual reproduction
A
genetically identical offspring w/ only 1 parent
- no gametes
4
Q
clone
A
group of genetically identical individuals
5
Q
sexual reproduction
A
genetically unique offspring w/ 2 parents
- fusion of two gametes (fertilization)
- forms diploid zygote
6
Q
cell division in protists are used for what ?
A
reproduction only
7
Q
cell division in the human body is used for what ?
A
- development
- growth
- repair
8
Q
binary fission
A
parent organism duplicates itself into two genetically identical individuals
- asexual reproduction
9
Q
do eukaryotes or prokaryotes hold more genes ?
A
eukaryotes; 7x more than prokaryotes
- 21000 vs 3000
10
Q
how many chromosomes are in a cell of an organism ?
A
depends on organism
11
Q
how many chromosomes are in humans, dogs, hedgehogs ?
A
46; 78; 90
12
Q
chromatin
A
DNA / protein that make up chromosomes
- long form of chromosomes
- coils up / distinct chromosomes when dividing
13
Q
sister chromatids
A
two identical chromatids on a duplicated chromosome
14
Q
centromere
A
spot where two sister chromatids of duplicated chromosome attach to each other
15
Q
when does chromosome consist of two identical sister chromatids ?
A
when cell is prepping to divide / before dividing
16
Q
cell cycle
A
ordered sequence of events from cell formation to duplication
- interphase
- mitotic phase
17
Q
interphase
A
growing stage of cell’ 90% of total cell cycle
- G1
- S phase
- G2
18
Q
G1
A
first gap; prep for duplication (cell growth)
- synthesize mRNA / proteins in prep for mitosis
19
Q
S phase
A
chromosome duplication (sister chromatids are formed)
- 50% of interphase
20
Q
G2
A
second gap; finish prep for cell division
- ensure all parts of cell are ready to divide
21
Q
mitotic (M) phase
A
cell division; 10% of total cell cycle
- mitosis
- cytokinesis
22
Q
mitosis
A
nucleus, contents, duplicated chromosomes divide
- form 2 identical daughter nuclei
23
Q
cytokinesis ?
A
begins at end of mitosis, cytoplasm splits into two separate daughter cells
24
Q
how often does an error occur in mitosis ?
A
~ 1/100,000; extremely accurate
25
1) prophase
- nuclear envelope disappears
- chromatin condenses
- mitotic spindles begin to form
26
2) metaphase
duplicated chromosomes line up in middle
27
3) anaphase
sister chromatids separate
- mitotic spindles pull sis. chromatids to opposite ends of cell
28
4) telophase / cytokinesis
daughter nuclei form and cell divides into two daughter cells
29
mitotic spindles
spindle microtubules for chromosome movement
- found in centrosomes
30
centrosomes
structure in *animal* cells where microtubules form / organize
- contain 2 centrioles
31
cytokinesis in animal cells vs plant cells
animal cells = cleavage furrow
plant cell = cell plate
32
how does cleavage furrow work ?
actin microfilaments contract toward each other, cleaving cell in two
33
how does cell plate work ?
vesicles collect along middle of cell and form new cell wall
34
what type of environment would constitute more cell division ?
a more abrasive environment
35
anchorage dependence
cell division requires cells to be attached to a surface
36
density dependent inhibition
cell division stops when cell is in-contact w/ another cell
37
what happens to density dependent inhibition when the cell is cancerous ?
cancer cells ignore this inhibition, they keep dividing forming clumps if overlapping cells
38
growth factors
protein secreted by body cells
- stimulates cells to divide
- different cells respond to different / combinations of growth factors
39
what is the biggest thing growth factors do ?
signals cell cycle to continue / stop
40
cell cycle control system
set of proteins tat trigger / coordinate events in cell cycle
- triggers mitosis
- checks if key components of cell are completed
- checkpoints
41
G1 checkpoint
signal allowing start of S phase
- checks cell size, nutrients, growth factors, DNA damage
42
what happens if G1 checkpoint never gets signaled ?
cell goes into G0 phase
- permanent non-dividing state
43
G0 cell examples
mature nerve / muscle cells
44
G2 checkpoint
after G2 is done, before mitotic (M) phase
- checks for DNA damage after chromosome replication
45
M checkpoint
(spindle checkpoint) after cell replication, before cytokinesis
-checks if all sister chromatids are correctly attached to microtubules
46
at which checkpoints are chromosomes duplicated ?
G2 / M
47
what is cancer
a disease of the cell cycle
- cells divide uncontrollably
48
what do cancer cells have altered that allow them to divide uncontrollably ?
cells w/ altered proteins that fail to be killed by immune system
49
tumor
abnormal mass of rapid growing tissue within normal tissue
- ignores cell cycle control system
- proceed past checkpoints w/o growth factors / can make own growth factors
50
benign tumor
abnormal mass of cells that remains in its original site
- removal by surgery
- no immediate threat unless left alone
51
malignant tumor
abnormal mass that can spread to neighboring tissue / other body parts
- cancerous
- spread via blood / lymph system and start forming new sites
52
cancer
disease due to malignant tumors within the bodt
53
metastasis
process of spreading cancer within the body beyond its original site
54
somatic cells
body cells
- have 46 chromosomes
- in mitosis; 23 *sets* of duplicated chromosomes
55
homologous chromsomes
homologs; two chromosomes that make a matched pair within diploid cell
- same centromere position, length, gene loci, staining, etc
- one from mom, one from dad
56
locus (loci)
site where specific gene is found on chromosome
- same gene is found in same loci on different chromosomes
57
sex chromosomes
X/Y chromsome; determines sex
- XX = female
- XY = male
58
autosomes
any chromosome other than X/Y
- doesnt affect sex
59
are all chromosomes for male and female homologous ?
no
- female = 23 homologs (22 autosomes + XX)
- male = 22 homologs (22 autosomes + XY)
60
life cycle
sequence of stages in life
- one adult to next generation adult
61
diploid (2n)
somatic cells
- set of homologous chromosomes (46)
- in organisms that reproduce sexually (one set from each parent)
62
human 2n = ?
46 (23 sets)
63
haploid (n)
sex cell
- single set of chromosomes (23)
- in organisms that reproduce sexually
64
human n = ?
23
65
gametes
sex (reproductive) cells (egg/sperm) formed by meiosis
- single set of chromosomes (23)
- fusing of two gametes forms zygote
66
fertilization
nucleus of sperm / egg combine
67
zygote
diploid fertilized egg
- one set of chromosomes from each parent
- mitosis of zygote makes all somatic cells
68
how many autosomes and which sex cells are in human sperm ?
22 autosomes and XY
69
meiosis is also known as what ?
reduction division
70
meiosis
divide single diploid cell into 4 genetically unique haploid daughter cells
- only sexual reproduction
- fertilization restores diploid state
- duplication of chromosomes followed by two cell divisions
71
meiosis I
crossing over of chromosomes from parents occurs and homologs split
- homologs separate
72
prophase I
- chromosomes condense
- homologs pair
- non-sister chromatids of homologs cross over
73
metaphase I
- microtubules attach to individual chromosomes
- homologs line up in middle next to each other
74
anaphase I
homologs separate to opposite ends
75
meiosis II
sister chromatids separate
- like mitosis but x2 (2 cells into 4 haploid cells)
76
tetrad orientation equation
2^n
- n = haploid # of organism
77
total # of possible tetrad orientations in humans ?
human n = 23
2^23 ~ 8mil
78
organisms w/ a diploid # of 10 have how many possible tetrad orientations ?
32;
2n = 10 ---> n = 5
2^5 = 32
79
crossing over
homolog non-sister chromatid synapsis during prophase I
- where loci swap genes
80
chiasma
site where crossing over between non-sister chromatids occur
81
recombinant chromosomes
chromosome name after crossing over
82
how many crossing overs occur in a human chromosome on average ?
1-3
83
are chromosomes in gametes going to look like chromosomes in skin cells ?
no; gametes have half the # of chromosomes compared to autosomes and more varied (cut/paste) segments from a homolog pair
84
nondisjunction
anaphase in mitosis / meiosis homologs / sister chromatids fail to separate
85
how does nondisjunction affect a fertilized zygote ?
that zygote will transmit abnormal # of chromosomes to all of its cells
- 10-30% of all human conceptions
- main reason for miscarriages
86
nondisjunction in meiosis I will affect the chromosomes of the 4 haploid daughter cells how ?
2 cells = n +1
2 cells = n - 1
87
nondisjunction in meiosis II will affect the chromosomes of the 4 haploid daughter cells how
2 cells = n
1 cell = n - 1
1 cell = n + 1
88
how could nondisjunction turn a gamete diploid ?
if in meiosis I and II all chromosomes are affected
- all chromosomes in meiosis I pulled into 1 daughter cell
- all chromosomes in meiosis II pulled into 1 daughter cell
89
karyotype
display of metaphase chromosomes by descending shape / size
- 46 chromosomes total (22 homologs / 1 pair sex chromosomes)
90
male sex chromosomes
XY
91
female sex chromosomes
XX
92
normal female karyotype will display how many homologs ?
23 homologs (22 homologs and XX)
93
normal male karyotype will display how many homologs ?
22 homologs (22 homologs and XY)
94
trisomy 21
disorder w/ extra chromosome 21 (3 total)
- heart / respiratory defects
- varying lvls of mental retardation
- majority cases of abnormal chromosomes
95
what can abnormal chromosome #s lead to ?
spontaneous embryo abortion (miscarriage)
96
down syndrome
condition of having trisomy 21
- 1/850 kids
- all / half of all affected sexually underdeveloped / sterile
- 50% all female eggs have extra chromosome
- risk of birthing child w/ disorder starts to increase at 40+
97
will abnormal amounts of X/Y sex chromosomes compared to abnormal amounts of autosome chromosomes have more of an affect on the child ?
no, abnormal autosome chromosome # affects child more
98
characteristic of the Y sex chromosome
small and few genes
99
can people afford to live with only one X sex chromosome ?
yes;
- males already only have 1 X chromosome - females can survive w/ only 1 because they have a set
100
klinefelter syndrome
extra X chromosome in men (XXY, XXXY, XXXXY)
- more X chromosomes = more likely for harmful disorders
101
extra X in females are shown in person how ?
- slightly taller
- higher risk of learning disabilities
- really cannot distinguish from normal XX
102
extra Y in males are shown in person how ?
normal male
- no symptoms
103
turner syndrome
Xo female
- lacks 1 X sex chromosome
- sterile / lesser development of secondary sex characteristics
- only case where 45 chromosomes in a human is NOT fatal
104
total # of autosomes in female w/ turner syndrome ?
44 + 1 X sex chromosome
105
how can new species arrive due to chromosomal errors ?
polyploidy; 2n = 4
meiosis fails ---> gametes form by mitosis
2n gamete + 2n gamete = 4n zygote
new species (diff. chromosome #) w/ only ONE generation
106
polyploidy
more than 2 sets of homolog chromosomes
107
colchicine
disrupt microtubule formation ---> no separation of chromosomes
- new species due to new chromosome #
108
chromosome breakage caused by ?
- errors in meiosis
- damaging agents (radiation); mutagens / mutagenesis
109
chromosome fragment
at least 1 nucleotide
110
deletion
fragment becomes detached from chromosome
111
duplication
repeated part of chromosome due to re-entry of a chromosome fragment from homolog
112
inversion
re-attaching fragment to same chromosome but in reverse orientation
113
which forms of chromosome breakages are more severe ?
deletion / duplication
- complete loss / double fragment in one chromosome
114
why are inversions and translocation not as severe as deletion / duplication ?
still have the gene, just not correct
115
"cry of the cat" syndrome
deletion in chromosome 5;
- developmental disabilities
- smaller head / unusual facial features
- shrill cat-like cry
116
myelogenous leukemia (CML)
translocation of chromosome 22 w/ tip of chromosome 9;
117
is cancer caused by chromosomal mutations heritable ?
no not usually;
- chromosomal mutations are usually in somatic cellsho
118
how is reciprocal translocation different than crossing over
reciprocal translocation is swapping of fragments between NON homologs
- crossing over is in a pair of homologs
