Reproduction (CH2) Flashcards
What stages are contained in interphase?
G1, S, G2
G1:
-Cells create organelles for energy and protein function.
-Cell size increases
S:
-DNA is replicated
-Chromatids (strands of DNA) are held together by centromere
G2:
-More cell growth
-Organelles replicated in preparation for mitosis
G0:
Cell performs function with no intentions of dividing
Cyclins
Bind to cyclin-dependent kinases (CDK)
Why do cyclins bind to CDH?
To activate transcription factors for the next stage of the cell cycle
In what cells does mitosis occur?
Somatic cells
Mitosis: Prophase
-Chromosomes condense
-Nuclear membrane dissolves
-Nucleoli dissapear
-Spindle apparatus forms
-Kinetochore of each chromosome is contacted by spindle fiber
Mitosis: Metaphase
-Chromosomes line up on metaphase plate
Mitosis: Anaphase
-Sister chromatids are separated and pulled to opposite poles
Mitosis: Telophase
-Nuclear membrane reforms
-Spindle apparatus dissappears
Cytokinesis (M Phase)
-Cytosol and organelles are split between two daughter cells
In what type of cells does meiosis occur in?
Germ cells (germatocytes)
What is produced by mitosis?
2 genetically identical daughter cells
What is produced by meiosis?
4 nonidentical haploid sex cells (gametes)
How many rounds of replication are in meiosis?
1
How many rounds of division are in meiosis?
2
In meiosis 1, what are separated?
Homologous pairs
What are homologous pairs?
Chromosomes that are given the same number, but are opposite parental origin (i.e. chromosome 13 from mom and chromosome 13 from dad)
Meiosis: Prophase 1
Same as mitosis but with some differences:
-Homologous pairs come together and intertwine (AKA synapsis)
-The tetrad (4) of chromatids perform crossing over
Crossing over accounts for which of Mendel’s laws?
Mendel’s second law (independent assortment)
Meiosis: Metaphase 1
-Homologous pairs line up on opposite sides of metaphase plate
Meiosis: Anaphase 1
-Homologous pairs are pulled to opposite poles of the cell (this accounts for Mendel’s first law of segregation)
Meiosis: Telophase 1
-Chromosomes may or may not fully decondense
-Cells may enter interkinesis after cytokinesis
What is separated in Meiosis 2?
Sister chromatids
How is meiosis 2 different from mitosis?
Functionally it is identical, the only difference is sister chromatids are separated instead of chromosomes
Where is sperm developed?
In the seminiferous tubules
Where are the seminiferous tubules?
In the testes
How are sperm nourished?
By Sertoli cells
What do the interstitial cells of Leydig do?
They secrete testosterone and other male sex hormones
Where are the testes located?
In the scrotum
What do seminal vesicles do?
They contribute fructose to nourish sperm and produce alkaline fluid
What does the prostate gland do?
It produces alkaline fluid
What do the bulbourethral glands do? (AKA Cowper’s gland)
Produces a clear, viscous fluid that cleans out remaining urine from the urethra and lubricates the urethra during sexual arousal
What is produced by spermatogenesis?
4 haploid sperm cells are produced from a spermatogonium
After the S phase, what are the germ cells called?
Primary spermatocytes
After meiosis 1, what are the germ cells called?
Secondary spermatocytes
After meiosis 2, what are the germ cells called?
Spermatids
After maturation, what are the germ cells called?
Spermatozoa
What is the head piece of sperm composed of?
-The genetic material
-Covered with acrosome
What is the acrosome?
A modified golgi apparatus that contains enzymes that helo the sperm fuse with and penetrate the ovum
What is the midpiece of sperm composed of?
-Contains many mitochondria
-Generates ATP from fructose
Where are ova produced?
In follicles
Where are follicles?
In the ovaries
What is formed during oogenesis?
1 haploid ovum and a variable number of polar bodies (usually 2)
Do polar bodies contain genetic info?
No, they are functionally inactive because they receive very little cytosol and organelles
What phase are primary oocytes arrested in?
Prophase 1
What phase is the secondary oocyte (the ovulated egg) arrested in?
Metaphase 2
When will the ovum complete meiosis 2?
When it is fertilized
What is the zona pellucida?
-An acellular mixture of glycoproteins that protects the oocyte.
-Contains compounds necessary for sperm binding
-Also contains the corona radiata
What is the corona radiata?
A layer of cells that adheres to the oocyte during ovulation
Where is GnRH released from?
The hypothalamus
What hormones does GnRH trigger to be released?
FSH and LH
In males, what does FSH trigger?
Sertoli cells and spermatogenesis
In males, what does LH trigger?
Causes Leydig cells to produce testosterone
In females, what does FSH trigger?
Development of ovarian follicles
In females, what does LH trigger?
Ovulation
What hormones do FSH and LH also trigger?
Testosterone, estrogen, and progesterone
What are the phases of the menstrual cycle?
-Follicular
-Ovulation
-Luteal
-Menstruation
In the follicular phase, what hormones are released?
-GnRH (which triggers FSH and LH)
-FSH triggers follicular development
-FSH and LH trigger estrogen
-Estrogen establishes uterine lining
In the ovulatory phase, what hormones are released?
-LH surge triggers ovulation
-LH surge is triggered by estrogen meeting a threshold, which causes a switch from negative to positive feedback
In the luteal phase, which hormones are released and inhibited?
-High estrogen and progesterone levels cause negative feedback on GnRH, LH, and FSH
-Progesterone maintains uterine lining
-Follicle ruptures releasing egg
In menstruation, which hormones are released and inhibited?
-Occurs if there is no fertilization
-Estrogen and progesterone levels drop
-Endometrial lining sloughs off
-Block on GnRH is removed
If fertilization does occur, what hormone is produced?
hCG is produced by the blastula
What does hCG do?
Acts as an LH analog to maintain the corpus luteum
When do hCG levels drop off?
Near the end of the first trimester, because the placenta takes over progesterone production
In menopause, which hormones are no longer produced?
Estrogen and progesterone
In menopause, which hormones are increased?
LH and FSH
