Biology Chapter 2 Flashcards
(197 cards)
1
Q
autosomal cells are ______
A
diploid (2n)
2
Q
diploid
A
contain two copies of each chromosome
3
Q
germ cells are ______
A
haploid (n)
4
Q
haploid
A
containing only one copy of each chromosome
5
Q
eukaryotic cells replicate through _______
A
cell cycle
6
Q
interphase
A
first three stages of cell cycle (longest part)
- G1, S, and G2
7
Q
G0 stage
A
cell is simply living and carrying out its functions
- do not divide
8
Q
G1 stage
A
- cell increases in size
- cell creates organelles for energy and protein production
9
Q
What is there between G1 and S?
A
restriction point
10
Q
S stage
A
cell replicates its genetic material
- number of chromatids double but ploidy stays the same
11
Q
G2 stage
A
cell pass through another quality control checkpoint
12
Q
What is checked during the G2 stage?
A
- cell has enough organelles and cytoplasm for 2 daughter cells
- makes sure DNA replication proceeded correctly
13
Q
M stage
A
includes mitosis and cytokinesis
14
Q
How many phases does mitosis have?
A
4 phases
15
Q
cytokinesis
A
splitting of the cytoplasm and organelles between the two daughter cells
16
Q
What controls the cell cycle?
A
checkpoints
17
Q
What is checked during G1/S checkpoint?
A
determines if condition of the DNA is good enough for synthesis
18
Q
What happens when DNA is not in good condition at G1/S checkpoint?
A
cell goes into arrest until DNA has been repaired
19
Q
What is the main protein in control of DNA repair for G1/S checkpoint?
A
p53
20
Q
p53 protein also plays a role in G2/M checkpoint
A
True
21
Q
What are the molecules responsible for the cell cycle?
A
cyclins and cyclin-dependent kinases (CDK)
22
Q
What do CDKs require in order to be activated?
A
presence of right cyclins
23
Q
What complex can phosphorylate transcription factors?
A
CDK-cyclin complex
24
Q
transcription factors
A
promote transcription of genes required for next stage of cell cycle
25
What can deranged cell cycle control and damaged cells undergoing mitosis lead to?
cancer
26
What is the gene that produces p53?
TP53
27
What does mutation of TP53 do?
cell cycle is not stopped to repair damaged DNA
- causes mutations to accumulate
28
What is caused by cancer cells undergoing rapid cell division?
tumors
29
metastasis
cancer spreading to other parts
30
mitosis
process by which two identical daughter cells are created
31
somatic cells
cells not involved in sexual reproduction
32
prophase
- condensation of the chromatin in to chromosomes
- centriole pairs separate and move toward opposite poles of cell
33
centriole pairs
- located at centrosome
- nuclear membrane dissolves
- responsible for correct division of dna
34
centrosome
region outside nucleus
35
What happens once centrioles migrate to opposite poles?
form spindle fibers
36
What are the spindle fibers made of?
microtubules
37
What are the two microtubule organizing centers of the cell?
1. basal body
2. centrosome
38
aster
microtubules that anchor centrioles to cell membrane
39
kineotchore
protein structures located on centromeres that serve as attachment points for specific fibers
40
metaphase
chromosomes are aligned at metaphase plate
41
anaphase
- centromeres split (each chromatid has its own distinct centromere)
- sister chromatids separate
- sister chromatids are pulled toward opposite poles of cell by shortening of the kinetochore fibers
42
telophase
reverse of prophase
- spindle apparatus disappears
- nuclear membrane reforms around each set of chromosomes
- nucleoli reappears
- chromosomes uncoil
43
each cell undergoes a finite number of divisions before programmed cell death
True
44
For what cells does meiosis occur in?
gametocytes (germ cells)
45
meiosis
results in up to four nonidentical sex cells (gametes)
46
Meiosis consists of _____
one round of replication and two rounds of division
47
Meiosis I
reductional division
48
reductional division
homologous chromosomes being separated
49
Meiosis II
equational division
50
equational division
separation of sister chromatids without change in ploidy
51
prophase I
- chromatin condenses into chromosomes
- spindle apparatus forms
- nucleoli and nuclear membrane disappear
52
What occurs uniquely in prophase I?
- synapsis occurs forming a tetrad
- crossing over occurs
53
synapsis
homologous chromosomes come together and intertwine
54
synaptonemal complex
group of proteins holding homologous chromosomes together
55
crossing over
process in which chromatids break at chiasma and exchange equivalent pieces of DNA
56
chiasma
point of contact for chromatids
57
What is caused by crossing over?
genetic recombination
58
linkage
refers to tendency for genes to be inherited together
- genes located farther are less likely to be inherited together
- vice versa
59
independent assortment
inheritance of one allele has one effect on the likelihood of inheriting certain alleles for other genes
- explained by crossing over
60
metaphase I
- tetrads align at metaphase plate
61
What is unique to metaphase I?
- each homologous pair (tetrad) attaches to a separate spindle fiber by its kinetochore (held by one spindle fiber)
62
anaphase I
- disjunction occurs
63
disjunction
homologous pairs separate and are pulled to opposite poles of the cell
64
law of segregation
each chromosome of paternal origin separates from maternal origin and either chromosome can end up in either daughter cell
65
telophase I
nuclear membrane forms around each new nucleus
- cytokinesis follows
66
interkinesis
short rest period between cell division
- chromosomes partially uncoil
67
prophase II
- nuclear envelope dissolves
- nucleoli disappear
- centrioles migrate to opposite poles
- spindle apparatus begins to form
68
metaphase II
chromosomes line up on metaphase plate
69
anaphase II
centromeres divide, separating chromosomes into sister chromatids
- chromatids are pulled to opposite poles by spindle fibers
70
telophase II
- nuclear membrane forms around each new nucleus
- cytokinesis follows and two daughter cells are formed
71
Which pair of chromosomes determines chromosomal sex?
23rd pair of chromosomes
72
ova can only carry ______
x chromosome
73
sperm can carry _______
either x or y chromosome
74
sex-linked disorders
mutations in genes carried by x chromosome
75
males are ______
hemizygous
76
hemizygous
many of genes on x chromosome because only have one copy
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males with a disease-causing allele on the unpaired part of x chromosome will necessarily express that allele
True
78
females may be ______ or ______
homozygous, heterozygous
79
most x-linked disorders are ______
recessively inherited
80
y chromosome contains very little genetic information
True
81
sex-determining region Y (SRY)
codes for transcription factor that initiates testis differentiation
- formation of male gomads
82
testes
developed from the primitive gonads
83
two functional components of testes
1. seminiferous tubules (highly coiled)
2. interstitial cells of Leydig
84
Where are sperm produced?
seminiferous tubules
85
What are sperms nourished by?
sertoli cells
86
What do the cells of Leydig do?
secrete testosterone and other male sex hormones
87
Where are the testes located?
scrotum
88
scrotum
external pouch that hangs below penis
- allows maintenance of temperature lower than body
89
Where are the sperm passed onto after they are formed?
epididymis
90
epididymis
where flagella gain motility
- where sperm are stored until ejaculation
91
Where do sperm travel through during ejaculation?
travel through vas deferens and then enter ejaculatory duct (posterior edge of prostate gland)
92
urethra
carries sperm through penis as they exit body
- formed through fusion of the two ejaculatory ducts
93
in males, reproductive and urinary systems share a common pathway
True
94
Combined effort of which parts produce the seminal fluid?
- seminal vesicles
- prostate gland
- bulbourethral gland
95
seminal vesicles
contribute fructose to nourish sperm
96
What do both seminal vesicles and prostate gland give to the seminal fluid?
mildly alkaline properties so sperm can survive in the relative acidity of female reproductive tract
97
bulbourethral (Cowper's) glands
- produce clear viscous fluid that cleans out any remnants of urine
- lubricates the urethra during sexual arousal
98
What is the combination of sperm and seminal fluid known as?
semen
99
spermatogenesis
formation of four haploid sperm through meiosis per spermatogonium
100
Where does spermatogenesis occur?
seminiferous tubules
101
spermatogogonia
diploid stem cells of males
102
Spermatogonia, after replicating genetic material (S stage), develop into _____ (for males)
diploid primary spermatocytes
103
What results after first meiotic division (for males)?
haploid secondary spermatocytes
104
What is generated after meiosis II? (for males)
haploid spermatids
105
What is formed after spermatids undergo maturation?
mature spermatozoa
106
structure of mature sperm
- head
- midpiece
- flagellum
107
sperm midpiece
- filled with mitochondria
108
Why is mitochondria needed in a mature sperm?
to generate the energy for swimming through the female reproductive tract to reach the ovum in the fallopian tubes
109
sperm head
covered by a cap known as an acrosome
- necessary to penetrate ovum
110
gonad
organ that produces gametes
111
What is the male gonad?
testes
112
What is the female goand?
ovaries
113
What do the ovaries produce?
estrogen and progesterone
114
What is anther word for eggs?
ova
115
follicles
multilayered sacs that contain, nourish, and protect immature ova
116
Each ovary consists of thousands of _____
follicles
117
Between puberty and menopause, how many eggs per month is ovulated into the peritoneal sac?
one
118
peritoneal sac
lines the abdominal cavity
119
ova then is drawn into the ________ from the peritoneal sac
fallopian tube/oviduct
120
fallopian tube/oviduct
lined with cilia to propel the egg forward
121
uterus
site of fetal development
- connected to the fallopian tubes
122
cervix
lower end of the uterus which connects to the vaginal canal
123
vaginal canal
where sperm are deposited during intercourse
124
vulva
collectively refers to the external parts of the female genital organs
125
oogenesis
production of female gametes
126
like males, there is an unending supply of stem cells analogous to spermatogonia in females
False, all the oogonia a female will ever have are formed during fetal development
127
primary oocytes
oogonia that have already undergone DNA replication (2n)
128
Where are primary oocytes arrested?
In prophase I
129
menarche
the first menstrual cycle
- during this stage, one primary oocyte per month will complete meiosis I
130
secondary oocyte
produced after a primary oocyte completes meiosis I along with a polar body
131
What results from unequal cytokinesis?
a secondary oocyte and a polar body
- ample cytoplasm is distributed to one daughter cell and nearly one to the other
132
Where is the secondary oocyte arrested?
in metaphase II until fertilization occurs (then finishes remainder of meiosis II)
133
2 layers surrounding oocytes
1. zona pellucida
2. corona radiata
134
zona pellucida
- surrounds actual oocyte
- an acellular mixture of glycoproteins that protect the oocyte
- contains compounds necessary for sperm cell binding
135
corona radiata
- lies outside the zona pellucida
- layer of cells that adheres to the oocyte during ovulation
136
When is meiosis II triggered?
when a sperm cell penetrates layers of oocyte with the help of acrosomal enzymes
137
What does the secondary oocyte split into when it undergoes the second meiotic division?
mature ovum and another polar body
138
a mature ovum is a very large cell
True
139
What does the ovum contribute to the zygote?
- half of the DNA
- all of the cytoplasm
- organnelles
- RNA (for early cellular processes)
140
What does the sperm contribute to the zygote?
half of the dna
141
Upon completion of ______, the haploid pronuclei of the sperm and ovum join to create a diploid zygote
meiosis II
142
the ability to reproduce is under hormonal control
True
143
gonadotropin-releasing hormone (GnRH)
triggers the anterior pituitary gland to synthesize and release FSH and LH
144
Which hormones trigger the production of other sex hormones (that develop and maintain the reproductive system)?
- follicle-stimulating hormone (FSH)
- luteinizing hormone (LH)
145
fetal period
from nine weeks after fertilization until birth
146
during fetal period, presence of Y chromosome leads to production of adrogens (for males)
True
147
How is androgen production for the duration of infancy and childhood?
low
148
When does testosterone levels increase dramatically?
during puberty; sperm production begins
149
____ stimulates Sertoli cells and triggers sperm maturation
FSH
150
_____ causes the interstitial cells to produce testosterone
LH
151
What causes development of secondary sexual characteristics?
testosterone
152
How long does testosterone production remain high?
remains high into adulthood
- declines with age
153
Estrogens are secreted in response to ____
FSH
154
What does estrogen do for the embryo?
stimulates development of the reproductive tract
155
What does estrogen do for adults?
thickens the lining of the uterus each month in preparation for the implantation of a zygote
156
endometrium
uterus
157
What secretes progesterone?
corpus luteum in response to LH
158
corpus luteum
remains of the ovarian follicle following ovulation
159
progesterone
involved in the development and maintenance of the endometrium
160
What supplies the progesterone by the end of the first trimester of a pregnancy?
placenta
161
What happens to the corpus luteum by the end of the first trimester of a pregnancy?
it atrophies (wastes away) and ceases to function
162
menstrual cycle
estrogen and progesterone levels rise and fall in a cyclic pattern
- in response, the endometrial lining will grow and be shed
163
How many events are in a menstrual cycle?
4 events
164
What are the four events of the menstrual cycle?
- follicular phase
- ovulation
- luteal phase
- menstruation
165
When does the follicular phase begin?
when the menstrual flow begins
166
menstrual flow
sheds the uterine lining of the previous cycle
167
What does decreased concentrations of estrogen and progesterone in the follicular phase?
increased secretion of GnRH
168
What does higher concentrations of GnRH in the follicular phase cause?
increased secretions of both FSH and LH
169
What is developed by increased secretions of FSH and LH in the follicular phase?
several ovarian follicles
170
What do the follicles created in the follicular phase produce?
estrogen
171
What feedback effects does estrogen have in the follicular phase?
negative feedback effects
- causes GnRH, LH, and FSH to level off
172
What does estrogen do in the follicular phase?
stimulates regrowth of the endometrial lining, which stimulates vascularization and glandularization of the decidua
173
What happens to estrogen levels in the late follicular phase?
developing follicles secrete higher and higher concentrations of estrogen
- reach a threshold that ends up in positive feedback
174
What does the high levels of estrogen in the late follicular phase cause?
a spike in GnRH, LH, and FSH levels
175
What does the surge in LH in the late follicular phase induce?
ovulation
176
ovulation
release of the ovum from the ovary into the abdominal cavity
177
What does LH cause after ovulation?
causes the ruptured follicle to form the corpus luteum (secretes progesterone)
178
What does estrogen do?
regenerate the uterine lining
179
What does progesterone do?
maintains uterine lining for implantation
180
What happens to progesterone levels in the luteal phase?
begin to rise while estrogen levels remain high
181
What does the high levels of progesterone cause in the luteal phase?
causes negative feedback on GnRH, FSH, and LH
- prevents ovulation of multiple eggs
182
menstruation happens assuming that implantation does not occur
True
183
menstruation
- corpus luteum loses its stimulation from LH
- progesterone levels decline
- uterine lining is slughed off
184
What does the loos of high levels of estrogen and progesterone during menstruation do?
removes the block on GnRH so that the next cycle can begin
185
What does the resulting zygote develop into if fertilization has occurred?
blastocyst
186
blastocyst
- implants in the uterine lining
- secretes human chorionic gonadotropin (hCG)
187
human chorionic gonadotropin (hCG)
- analog of LH
- can stimulate LH receptors
- maintains corpus luteum
188
Which trimester is hCG critical for and why?
first trimester
- because the estrogen and progesterone secreted by the corpus lueum keep the uterine lining in place
189
During which trimester does hCG levels decline and why?
second trimester
- because placenta has grown sufficiently to secrete enough progesterone and estrogen by itself
190
What feedback do the high levels of estrogen and progesterone continue to serve during pregnancy?
negative feedback on GnRH secretion
191
With age, the ovaries become less sensitive to ____ and _____
FSH, LH
192
What happens during menopause?
- ovarian atrophy
- endometrium also atrophies
- blood levels of FSH and LH rise
193
What causes the endometrium to atrophy during menopause?
estrogen and progesterone levels dropping
194
What causes the blood levels of FSH and LH to rise?
removal of the negative feedback on FSH and LH
195
SEVE(N) UP
mnemonic for sperm pathway through male reproductive system
- Seminiferous tubules
- Epididymis
- Vas deferens
- Ejaculatory duct
- Nothing
- Urethra
- Penis
196
Est; est; pro; pro
Mnemonic for estrogen and progesterone functions
- Estrogen
- establishes and
- progesterone
- protects the endometrium
197
seX is X-linked
mnemonic for X chromosome x-llnked disorders
