Reproduction Flashcards
Name the 5 stages of the cell cycle.
- G1 stage (Presynthetic stage)
- S stage (Syntheis of DNA)
- G2 stage (Postsynthetic stage)
- M stage (Mitosis)
- G0 stage
What occurs during the G1 stage (Presynthetic stage) of the cell cycle?
Cells create organelles for energy and protein production, while increasing their size.
What occurs during the S stage (Synthesis of DNA) of the cell cycle?
Replication of DNA. Strands of DNA, termed chromatin, are held together at the centromere.
What occurs during the G2 stage (Postsynthetic stage) of the cell cycle?
Further cell growth and replication of organelles in preparation for mitosis.
What occurs during the M stage (Mitosis) of the cell cycle?
Mitosis and cytokinesis.
What occurs during the G0 stage of the cell cycle?
The cell is simply living and serving its function without and preparation for division.
The first 3 stages (G1, S, and G2) are known collectively as?
Interphase
Interphase includes what 3 stages of the cell cycle?
- G1 stage (Presynthetic stage)
- S stage (Synthesis of DNA)
- G2 stage (Postsynthetic stage)
Define cytokinesis.
The separation of the cytoplasm and organelles so that each daughter cell has sufficient supplies to survive on its own.
What protein plays a major role in the G1/S and G2/M checkpoints?
p53
What is the purpose of the G1/S checkpoint?
The cell determines if the DNA is in good enough condition for synthesis.
What is the purpose of the G2/M checkpoint?
The cell is concerned with ensuring the cell has achieved adequate size and the organelles have been properly replicated to support two daughter cells.
What are the 2 molecules responsible for the cell cycle?
Cyclin and Cyclin-dependent kinases (CDK)
Note: Cyclins bind to cyclin-dependent kinases activating the CDK-cyclin complex.
Define cyclin-dependent kinases.
Group of protein kinases that are activated by the formation of a complex with a cyclin and are involved in the regulation of the cell cycle.
Name the 2 types of cyclin-dependent kinases (CDK).
- Serine
2. Threonine
Define cyclins.
Any number of proteins associated with the cell cycle of cell division that are thought to initiate certain processes of mitosis.
What is the difference between a chromatin, chromosome, and chromatid?
Chromatin: chromosomes in the form of long thin strands during interphase of the cell cycle.
Chromosome: chromatin condensed during cell division
Chromatid: single replicated chromosome becoming two sister chromatids
Name the 4 G1/S cyclins.
- Cyclin A/CDK2 (active in S phase)
- Cyclin D/CDK4 (regulate G1 to S transition)
- Cyclin D/CDK6 (regulate G1 to S transition)
- Cyclin E/CDK2 (regulate G1 to S transition)
Name the G2/M cyclin(s).
Cyclin B/CDK1 (regulates progression from G2 to M phase)
Name the 4 phases of mitosis.
- Prophase
- Metaphase
- Anaphase
- Telophase
Mnemonic: PMAT
Mitosis production results in what?
2 genetically identical diploid daughter cells from a single cell.
Note: occurs in somatic cells
Diploid cells have how many copies of chromosomes?
2
Haploid cells have how many copies of chromosomes?
1
What happens during prophase of mitosis?
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus apparatus begins to form.
Note: there are 2 chromosomes during prophase
What happens during metaphase of mitosis?
Chromosomes line up along the metaphase plate.
Note: there are 2 chromosomes during metaphase.
What happens during anaphase of mitosis?
Sister chromatids are separated and pulled to opposite poles.
Note: there are 4 chromosomes during anaphase
What happens during telophase of mitosis?
The nuclear membrane reforms, spindle apparatus disappears, and cytosol and organelles are split between the 2 daughter cells through cytokinesis.
Note: there are 4 chromosomes during telophase
During which phase of mitosis is the kinetochore of each chromosome contacted by a spindle fiber?
During prophase
Name the 4 nucleobases in DNA.
- Adenine (purine)
- Thymine (pyrimidine)
- Guanine (purine)
4 Cytosine (pyrimidine)
Name the 2 base pairs found in DNA.
Hint: there are 4 nucleobases
- Adenine-Thymine [A-T]
- Guanine-Cytosine [G-C]
Note: purine base pairs with pyrimidine
Define replication.
The process by which an exact copy of a polynucleotide strand, such as DNA, is duplicated/produced.
Define transcription.
The process by which a polynucleotide, such as DNA, is transcribed (copied) into complementary RNA, termed mRNA.
DNA –> mRNA
Note: Adenine base pairs with Uracil, not Thymine
Define translation.
The process by which mRNA is translated (decoded) by tRNA to produce the specific sequence of amino acids in a polypeptide chain (proteins).
mRNA –> protein
Note: this process occurs in the ribosome of cells & adenine base pairs with uracil, not thymine
Define the central dogma of biology.
DNA -(transcription)-> RNA -(translation)-> Protien
Differentiate between mitosis and meiosis.
Mitosis: occurs in somatic tissue and results in 2 identical daughter cells
Meiosis: occurs in germ cells (gametocytes) and results in 4 unidentical sex cells (gametes)
Describe the pathway of sperm through the male reproductive system.
Seminiferous tubules -> Epididymis -> Vas deferens -> Ejaculatory duct -> Urethra -> Penis
Mnemonic: SEVE(N) UP
Meiosis production results in what?
4 non-identical haploid sex cells (gametes).
Note: occurs in germ cells (gametocytes)
Define spermatogenesis.
The formation of haploid sperm through meiosis, occurring in the seminiferous tubules.
Note: spermatogenesis results in 4 functional sperm for each spermatogonium.
Describe the process of spermatogenesis.
(1) Spermatogonia -[S stage]->
(2) Primary Spermatocytes -[Meiosis I]->
(3) Secondary Spermatocytes -[Meiosis II]->
(4) Spermatids -[Maturation]->
(5) Spermatozoa
Note: steps 1 and 2 are diploid; steps 3 and 4 are haploid
Which chromosome can only a female ovum carry?
The X chromosome
Which chromosome can a male sperm carry?
The X or Y chromosome
Define hemizygous gene.
Contains no allelic counterpart or is present as only a single copy of a gene in a diploid cell.
Note: males are hemizygous
Name the 2 functional components of the testes.
- Seminiferous tubules
2. Interstitial cells of Leydig
Sperm are nourished by which cells in the seminiferous tubules?
Sertoli cells
Name the 2 types of hormones secreted by the interstitial cells of Leydig in the male reproductive tract.
- Testosterone
2. Androgens
In what part of the male reproductive system are do sperm gain motility and are stored until ejaculation?
The epididymis
Where is seminal fluid produced?
Hint: there are 3 components
- Seminal vesicles
- Prostate gland
- Bulbourethral gland
What are the function(s) of seminal vesicles in the male reproductive system?
Contribute fructose to nourish sperm and provides the mild alkaline fluid necessary for sperm to survive in the slightly acidic female reproductive tract.
What are the function(s) of the prostate gland in the male reproductive tract?
Provides the mild alkaline fluid necessary for sperm to survive in the slightly acidic female reproductive tract.
What are the function(s) of the bulbourethral (Cowper’s) gland in the male reproductive tract?
Produces clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal.
Name the 2 types of hormones secreted by the ovaries in the female reproductive tract.
- Estrogen
2. Progesterone
What are the function(s) of follicles in the female reproductive tract?
Contain, nourish, and protect immature ova (eggs).
Define oogenesis.
One haploid ovum and a variable number of polar bodies are formed in the oogonium.
Describe the process of oogenesis.
(1) Oogonia
- (DNA replication at birth)->
(2) Primary Oocytes
- (prophase I; ovulated egg each month)->
(3. ) Secondary Oocytes
- (metaphase II; fertilized egg meiosis II)->
(4) Ovum
Name the 2 layers surrounding Oocytes.
- Zona pellucida
- Corona radiata
Mnemonic: females in zona drink corona
What are the function(s) of the zona pellucida in the female reproductive tract?
Surrounding acellular mixture of glycoproteins that protects the oocyte and aids in sperm binding.
What function(s) does the corona radiata in the female reproductive tract serve?
Adheres the oocyte outside of the zona pellucida during ovulation.
Define zygote.
The product of meiosis II when the haploid pronuclei of the sperm and the ovum join.
The gonadotropin-releasing hormone (GnRH) targets (a.) which gland and releases (b.) which hormone(s)?
a. Anterior pituitary gland
b. Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)
Name the gland that synthesizes the gonadotropin-releasing hormone (GnRH).
The hypothalamus
What are the function(s) of the follicle-stimulating hormone (FSH) in both the male and female reproductive tracts?
Male: FSH stimulates the testes (Sertoli cells) and triggers sperm maturation (Spermatids –> spermatozoa).
Female: FSH stimulates ovaries to release estrogen.
What are the function(s) of the luteinizing hormone (LH) in both the male and female reproductive tracts?
Male: LH stimulates testes (interstitial cells of Leydig) to secrete testosterone.
Female: LH stimulates the corpus luteum to secrete progesterone.
Define menstrual cycle.
A periodic growth and shedding of the endometrial lining in response to the rise and fall of estrogen and progesterone levels.
Name the 4 events of the menstrual cycle.
- Follicular phase
- Ovulation
- Luteal phase
- Menstruation
What event(s) occur during the follicular phase of the menstrual cycle?
Hint: GnRH, FSH, LH, estrogen, progesterone
- GnRH concentrations increase in response to decreased concentrations of estrogen & progesterone
- Higher GnRH concentration triggers secretion of FSH & LH to produce follicles
- Production of follicles increases estrogen secretion causing decreased concentration of GnRH, FSH, and LH
- Estrogen works to regrow endometrial lining
What event(s) occur during the ovulation phase of the menstrual cycle?
Hint: estrogen, GnRH, FSH, LH
- Developing follicles secrete higher and higher concentrations of estrogen
- Estrogen concentration reach a threshold causing production of GnRH, FSH, and LH
- Increasing concentrations of LH induces ovulation (release of ovum from ovary into abdominal cavity)
What event(s) occur during the luteal phase of the menstrual cycle?
Hint: GnRH, FSH, LH, estrogen, progesterone
- Proceeding ovulation, high concentrations of LH causes ruptured follicle to form corpus luteum
- Formation of corpus luteum results in secretion of progesterone
- High concentrations of progesterone causes a decrease in GnRH, FSH, and LH preventing ovulation of multiple eggs
What event(s) occur during the menstruation phase of the menstrual cycle?
Hint: GnRH, LH, estrogen, progesterone
- Decreased concentration of LH causes corpus luteum to lose stimulation
- Loss of stimulation in corpus luteum causes decreased production of progesterone and uterine lining is sloughed off
- Decreased concentrations of estrogen and progesterone stimulate GnRH secretion for next cycle
* assuming fertilization does not occur*
Define menopause.
Occurs when ovaries stop producing estrogen and progesterone, usually between the ages of 45 and 55. Menstruation stops and FSH and LH levels rise.
What is an acrosome? What organelles forms the acrosome?
The cap covering the head of a sperm which contains enzymes capable of penetrating the corona radiata and zona pellucida of the ovum, allowing for fertilization. It is a modified Golgi apparatus.
