🌱 MCAT Biology Review - 2 Flashcards
(140 cards)
1
Q
Which of the following is the correct sequence of the development of a mature sperm cell?
A
Spermatogonium→1° spermatocyte→2° spermatocyte→spermatid→spermatozoan
2
Q
At which point in a woman’s life cycle is the egg cell at prophase II?
A
From birth to menarche
3
Q
At which stage of mitotic division would one first visualize a defect in spindle apparatus attachment?
A
Metaphase
4
Q
What is the latest stage of cellular development during which radiolabeled deoxyadenine could be added?
A
S
5
Q
A physician diagnosing a granulosa cell tumor should look for a secondary cancer in which part of the reproductive tract?
A
Endometrium
6
Q
Upon ovulation, where is the oocyte released into?
A
Abdominal cavity
7
Q
At which point(s) in the cell cycle could chemotherapy effectively prevent cancer cell division?
A
I, II, and III
8
Q
Which of the following incorrectly pairs a structure of the male reproductive system with a feature?
A
Prostrate gland—surrounded by muscle to raise and lower the testes
9
Q
What is the last point in the meiotic cycle where the cell has a diploid number of chromosomes?
A
During telophase I
10
Q
Which of the following does NOT likely contribute to genetic variability?
A
Replication of the DNA during S stage
11
Q
What is a key difference between mitosis and meiosis?
A
In metaphase of mitosis, replicated chromosomes line up in single file; in metaphase II of meiosis, replicated chromosomes line up on opposite sides of the metaphase plate
12
Q
What happens to the nucleoli during prophase?
A
They disappear
13
Q
What is the likely genotype of an individual who is phenotypically female and has classic symptoms of a disease due to nondisjunction?
A
45,X
14
Q
During which phase of the menstrual cycle does progesterone concentration peak?
A
Luteal phase
15
Q
Which of the following would NOT be seen during pregnancy?
A
High levels of GnRH throughout the pregnancy
16
Q
What are the four phases of mitosis?
A
- Prophase
- Metaphase
- Anaphase
- Telophase
17
Q
What are the five stages of the cell cycle?
A
- G1
- S
- G2
- M
- G0 (offshoot of G1)
18
Q
What is the main protein in control of the G1/S checkpoint?
A
p53
19
Q
What characterizes the cells in G0 phase?
A
Cells are living and carrying out functions without preparation for division
20
Q
What happens to chromosomes during interphase?
A
They are in a less condensed form known as chromatin
21
Q
What are genetically identical daughter cells?
A
Cells that result from mitosis and are exact copies of the parent cell.
22
Q
What is the role of checkpoints in the cell cycle?
A
To ensure the cell is ready to proceed to the next phase, particularly checking DNA integrity and size.
23
Q
What occurs at the G1/S checkpoint?
A
The cell checks if the DNA is in good condition for synthesis.
24
Q
What is another name for the G1/S checkpoint?
A
Restriction point.
25
What happens if DNA damage is detected at the G1/S checkpoint?
The cell cycle is arrested until the DNA is repaired.
26
What is the main protein involved in cell cycle control?
p53.
27
What is the focus of the G2/M checkpoint?
To ensure adequate cell size and proper organelle replication.
28
What are cyclins and CDKs?
Cyclins are molecules that regulate the cell cycle, and CDKs (cyclin-dependent kinases) are activated by cyclins.
29
What is the function of the activated CDK-cyclin complex?
To phosphorylate transcription factors that promote gene transcription for the next cell cycle stage.
30
What can result from deranged cell cycle control?
Cancer.
31
What is the common mutation found in cancer related to cell cycle control?
Mutation of the TP53 gene.
32
What does mutation of the TP53 gene lead to?
Cells do not stop to repair damaged DNA, allowing mutations to accumulate.
33
What is metastasis?
The spread of cancerous cells to other tissues via the bloodstream or lymphatic systems.
34
How are cancer-causing genes classified?
Into oncogenes and tumor suppressor genes.
35
What are the four phases of mitosis?
Prophase, metaphase, anaphase, and telophase.
36
What happens during prophase?
Chromatin condenses into chromosomes, centrioles move to opposite poles, and the nuclear membrane dissolves.
37
What occurs during metaphase?
Chromosomes align at the metaphase plate.
38
What happens in anaphase?
Sister chromatids separate and are pulled toward opposite poles.
39
What is telophase?
The nuclear membrane reforms, chromosomes uncoil, and the spindle apparatus disappears.
40
What is cytokinesis?
The separation of the cytoplasm and organelles into two daughter cells.
41
How many divisions do human somatic cells undergo before programmed death?
Between 20 and 50.
42
What does the p53 tumor suppressor pathway induce in response to cellular stress?
Growth arrest and apoptosis.
43
What is RI-TATp53C’?
A peptide explored as a treatment for cancer that activates the p53 pathway.
44
What is the relationship between RI-TATp53C’ and endogenous p53?
RI-TATp53C’ requires endogenous p53 to induce cell cycle arrest.
45
What indicates that RI-TATp53C' induces cell arrest in G1?
The observation that cells treated with RI-TATp53C' have less DNA content.
46
What does a non-functional version of RI-TATp53C’ serve as in experiments?
A negative control.
47
What do the two different cancer cell lines used in the experiments represent?
One has endogenous p53 (TA3/St) and the other lacks p53 (H1299).
48
True or False: The ability of RI-TATp53C' to induce cell cycle arrest is independent of endogenous p53.
False.
49
What induces cell arrest in G1 due to increased proportion of cells with lower DNA content?
RI-TATp53C' requires a functional p53 pathway
## Footnote
Loss of RI-TATp53C' functionality occurs in the p53 -/- condition.
50
What are the five stages of the cell cycle?
* G1 phase
* S phase
* G2 phase
* M phase
* Cytokinesis
## Footnote
Each stage has specific features and functions.
51
What are the four phases of mitosis?
* Prophase
* Metaphase
* Anaphase
* Telophase
## Footnote
Each phase has distinct events that lead to cell division.
52
What is the result of meiosis in terms of daughter cells?
Up to four nonidentical sex cells (gametes)
## Footnote
Meiosis occurs in gametocytes and is distinct from mitosis.
53
What is the difference between homologous chromosomes and sister chromatids?
* Homologous chromosomes: separate chromosomes inherited from each parent
* Sister chromatids: identical strands of DNA connected at the centromere
## Footnote
Homologous chromosomes form pairs, while sister chromatids are copies of the same chromosome.
54
What is crossing over and why is it important?
Exchange of genetic material between homologous chromosomes
## Footnote
Increases genetic diversity and can unlink linked genes.
55
What occurs during prophase I of meiosis?
Chromatin condenses into chromosomes, spindle apparatus forms, and homologous chromosomes undergo synapsis
## Footnote
This results in tetrads, where crossing over can occur.
56
What is the significance of disjunction during anaphase I?
Homologous pairs separate to opposite poles, ensuring random distribution of chromosomes
## Footnote
This process supports Mendel's first law (of segregation).
57
What happens during telophase I of meiosis?
Nuclear membrane forms around each new nucleus and cytokinesis occurs
## Footnote
Each daughter cell is now haploid with n chromosomes.
58
What is the key difference between meiosis I and mitosis?
Meiosis I is reductional division, halving chromosome number; mitosis maintains it
## Footnote
Daughter cells from meiosis I have the haploid number of chromosomes.
59
What occurs during anaphase II of meiosis?
Centromeres divide, separating sister chromatids that move to opposite poles
## Footnote
This stage resembles anaphase in mitosis.
60
What is the output of meiosis II in terms of daughter cells?
Up to four haploid daughter cells
## Footnote
Each cell contains a unique combination of alleles.
61
What is the pathway of sperm through the male reproductive system?
* Seminiferous tubules
* Epididymis
* Vas deferens
* Ejaculatory duct
* Urethra
## Footnote
This pathway is summarized by the mnemonic SEVE(N) UP.
62
What are the two functional components of the testes?
* Seminiferous tubules
* Interstitial cells of Leydig
## Footnote
Seminiferous tubules produce sperm, while Leydig cells secrete testosterone.
63
What is the function of Sertoli cells?
Nourish developing sperm in the seminiferous tubules
## Footnote
They play a crucial role in spermatogenesis.
64
What does the term hemizygous refer to in males?
Having only one copy of genes on the X chromosome
## Footnote
This makes males more likely to express X-linked disorders.
65
What is the role of the SRY gene on the Y chromosome?
Codes for a transcription factor that initiates testis differentiation
## Footnote
This gene is crucial for male sex determination.
66
What is the function of seminal fluid in the male reproductive system?
Nourishes sperm and provides a medium for survival in the female reproductive tract
## Footnote
Produced by seminal vesicles, prostate gland, and bulbourethral gland.
67
What is spermatogenesis?
The formation of haploid sperm through meiosis
## Footnote
Occurs in the seminiferous tubules.
68
What are alkaline properties of seminal fluid important for?
To allow sperm to survive in the relative acidity of the female reproductive tract
## Footnote
Seminal fluid is produced by various glands, including the bulbourethral glands.
69
What is the term for the formation of haploid sperm through meiosis?
Spermatogenesis
70
What are spermatogonia?
Diploid stem cells in males that develop into primary spermatocytes
71
How many functional sperm result from one spermatogonium?
Four functional sperm
72
What components make up mature sperm?
* Head (containing genetic material) * Midpiece (generating ATP) * Flagellum (for motility)
73
What is the role of the acrosome in sperm?
Necessary to penetrate the ovum
74
What is oogenesis?
The production of female gametes
75
What are the primary oocytes arrested in?
Prophase I
76
What happens to the secondary oocyte if fertilization occurs?
Completes meiosis II
77
What surrounds oocytes and protects them?
* Zona pellucida * Corona radiata
78
What triggers the completion of meiosis II in secondary oocytes?
Sperm cell penetration
79
What is the role of GnRH before puberty?
To restrict production of gonadotropins
80
What hormones are released by the anterior pituitary in response to GnRH?
* Follicle-stimulating hormone (FSH) * Luteinizing hormone (LH)
81
What does testosterone do during male sexual development?
* Develops and maintains male reproductive system * Induces secondary sexual characteristics
82
What condition occurs if testosterone receptors are absent or defective?
Androgen insensitivity syndrome (AIS)
83
What do estrogens do in female sexual development?
* Develop and maintain female reproductive system * Induce secondary sexual characteristics
84
What is the mnemonic for the roles of estrogen and progesterone?
Estrogen establishes and progesterone protects the endometrium
85
What are the four phases of the menstrual cycle?
* Follicular phase * Ovulation * Luteal phase * Menstruation
86
What triggers ovulation?
Surge in luteinizing hormone (LH)
87
What happens to the corpus luteum if fertilization does not occur?
It atrophies and progesterone levels decline
88
What hormone does the blastocyst secrete after fertilization?
Human chorionic gonadotropin (hCG)
89
What physiological changes accompany menopause?
* Flushing * Hot flashes * Bloating * Headaches
90
What happens to FSH and LH levels during menopause?
They rise due to the loss of negative feedback
91
What is the role of the corpus luteum during early pregnancy?
Secretes estrogen and progesterone to maintain the uterine lining
92
What is unique about the division of primary oocytes during oogenesis?
It is characterized by unequal cytokinesis
93
Fill in the blank: The _______ is essential for sperm penetration of the ovum.
Acrosome
94
True or False: The secondary oocyte completes meiosis II before fertilization.
False
95
What are diploid (2n) cells?
Cells that have two copies of each chromosome
96
What are haploid (n) cells?
Cells that have one copy of each chromosome
97
What are the five stages of the cell cycle?
G1, S, G2, M, G0
98
What occurs during the G1 stage?
Cells create organelles for energy and protein production, and increase their size
99
What happens in the S stage of the cell cycle?
DNA is replicated
100
What is the role of p53 in the cell cycle?
It plays a role in the two major checkpoints of the cell cycle (G1 to S, G2 to M)
101
What is the result of mitosis?
Two genetically identical diploid daughter cells from a single cell
102
List the four phases of mitosis.
* Prophase
* Metaphase
* Anaphase
* Telophase
103
What occurs during prophase?
Chromosomes condense, nuclear membrane dissolves, centrioles migrate
104
During which phase do sister chromatids separate?
Anaphase
105
What happens during telophase?
Nuclear membrane reforms, and cytosol and organelles are split between the two daughter cells
106
What is the main purpose of meiosis?
To produce up to four nonidentical haploid sex cells (gametes)
107
What happens in prophase I of meiosis?
Homologous chromosomes come together and intertwine in synapsis
108
What is the chromosomal sex determination in humans?
XX is female and XY is male
109
What do Sertoli cells do?
Nourish sperm during their development
110
What hormone do interstitial cells of Leydig secrete?
Testosterone
111
What is the function of the acrosome in sperm?
Contains enzymes that help the sperm fuse with and penetrate the ovum
112
What is the difference between primary and secondary oocytes?
Primary oocytes are arrested in prophase I, while secondary oocytes are arrested in metaphase II
113
What hormones stimulate the development of ovarian follicles in females?
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
114
What triggers ovulation?
A sudden surge in LH
115
What occurs during the luteal phase of the menstrual cycle?
The corpus luteum produces progesterone to maintain the uterine lining
116
What happens if fertilization does not occur?
Menstruation occurs as the endometrial lining is shed
117
What is hCG and its role in pregnancy?
Human chorionic gonadotropin maintains the corpus luteum
118
At what age does menopause typically occur?
Between ages 45 and 55
119
What is the role of estrogen in the menstrual cycle?
Stimulates vascularization and glandularization of the decidua
120
Fill in the blank: The cell cycle's G0 stage is when the cell _______.
performs its functions without preparing for division
121
True or False: Cancer occurs when cell cycle control becomes deranged.
True
122
What are the final products of the second meiotic division in spermatogenesis?
Mature sperm, or spermatozoa
123
What stage are primary oocytes arrested in from birth until shortly before ovulation?
Prophase stage of meiosis I
124
What is the status of the egg cell at ovulation?
Haploid cell called a secondary oocyte, arrested in metaphase II
125
What must happen for a secondary oocyte to become a mature ovum?
Complete meiosis II upon sperm penetration
126
During what phase of the cell cycle does the spindle apparatus first interact with the kinetochore fibers?
Prophase
127
When is the latest point at which deoxyadenine can be added to DNA?
S stage
128
What role does estrogen play during the menstrual cycle?
Causes growth of the endometrial lining and promotes vascularization and glandularization
129
What happens to an oocyte after the ruptured ovarian follicle releases it?
It is drawn into the fallopian tube and can implant in the uterine wall if fertilized
130
What could be done to lower the number of cells undergoing mitosis?
Prevent DNA synthesis during S stage or interfere with processes during prophase or metaphase
131
Which glands secrete seminal fluid that combines with sperm?
Prostate gland, seminal vesicles, bulbourethral gland
132
What occurs during anaphase I of meiosis?
Homologous chromosomes are pulled to opposite poles
133
What is the significance of random fertilization during sexual reproduction?
It contributes to genetic variability
134
What key differences are observed between mitosis and meiosis during meiosis I?
Synapsis and crossing over occur; homologous chromosomes are separated
135
What happens to chromatin during prophase?
Condenses into chromosomes, spindle apparatus forms, nucleoli and nuclear membrane disappear
136
What does nondisjunction refer to?
Incorrect segregation of homologous chromosomes or sister chromatids
137
What hormone peaks during the luteal phase to support the endometrium?
Progesterone
138
What maintains progesterone secretion by the corpus luteum during the first trimester of pregnancy?
Human chorionic gonadotropin (hCG)
139
Fill in the blank: The egg cell is arrested in _______ at ovulation.
Metaphase II
140
True or False: The DNA should be copied precisely during the S stage.
True
