Biology Chapter 2: Reproduction Flashcards
Explain the difference between diploid and haploid
Diploid have 2 copies of each chromosome; haploid have one copy
What are the five stages of the cell cycle?
G1, S, G2, M, G0
What are the three stages that make up interphase?
G1, S, G2
What happens during the G1 stage?
cells create organelles for energy and protein production, while also increasing size.
What is the restriction point?
DNA is checked for quality, it must be passed for the cell to move into the S stage.
What happens during the S stage?
DNA is replicated - strands of DNA are called chromatids and are held together at the centromere.
What happens during the G2 stage?
further cell growth and replication of organelles in preparation for mitosis. Another quality checkpoint must be passed for the cell to pass into mitosis.
What happens during the M stage?
mitosis and cytokinesis occur
What happens during the G0 stage?
the cell performs its functions without any preparation for division.
What is p53?
plays a role in the two major checkpoints of the cell cycle (from G1 to S and G2 to M)
What is the significance of cyclins and cyclin-dependent kinases in the cell cycle?
rise and fall during the cell cycle. Cyclins bind to CDKs, phosphorylating and activating transcription factors for the next stage of the cell cycle.
When does cancer occur?
It occurs when cell cycle control becomes deranged, allowing damaged cells to undergo mitosis without regard to quality or quantity of the new cells produced. They may begin to produce factors that allow them to escape their site and invade or metastasize elsewhere.
What is the result of mitosis?
Two identical somatic cells
What are the 4 phases of mitosis?
prophase, metaphase, anaphase, telophase
What happens in prophase?
chromosomes condense, membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell and the spindle apparatus begins to form. the kinetochore of each chromosome is contacted by a spindle fiber.
What happens in metaphase?
Chromosomes line up along the metaphase plate.
What happens in anaphase?
sister chromatids are separated and pulled to opposite poles.
What happens in telophase?
nuclear membrane reforms, spindle apparatus disappears and cytosol and organelles are split between the two daughter cells through cytokinesis.
Where does meiosis occur?
In gameocytes, germ cells
What does meiosis produce?
up to 4 nonidentical haploid sex cells (gametes)
How many rounds of replication does meiosis have? Division?
1 round of replication and 2 rounds of division (reductional and the equational)
What happens in meiosis I?
homologous pairs of chromosomes are separated from each other
What are homologues?
chromosomes that are given the same number, but are of opposite parental origin
What is different in the prophase I of meiosis?
Same events occur, except that homologues come together and intertwine in a process called synapsis, this is when crossing over occurs
What is Mendel’s law of segregation?
Alleles separate from one another
What is Mendel’s law of random assortment?
Alleles sort independently of one another
What happens in meiosis II?
sister chromatids are separated from each other in a process functionally identical to mitosis.
What does hemizygous mean?
In men, referring to only having one X chromosome and one Y chromosome.
Can men be carriers of sex-linked diseases?
No, because they only have one x chromosome.
Where do sperm develop?
In the seminiferous tubules in the testes
What nourishes sperm?
Sertoli cells
What do interstitial cells (of Leydig) secrete in the male reproductive system?
secrete testosterone and other sex hormones (androgens)
What is the scrotum?
It is where the testes are located
Where are sperm held once formed?
In the epididymis - they gain motility and are stored until ejaculation.
What path does the sperm take during ejaculation?
through Vas Deferens to ejaculatory duct to urethra and out the penis.
What do the seminal vesicles do?
They nourish sperms with fructose and alkaline fluid
What two reproductive parts produce alkaline fluid?
prostate gland and seminal vesicles
What do the bulbourethral glands produce?
a clear viscous solution that cleans out any remnants of urine and lubricates the urethra during sexual arousal.
What is sperm?
the combination of sperms and fluids
After the S stage, what are sperm called?
Meiosis 1?
Meiosis 2?
Maturation?
primary spermatocytes
secondary spermatocytes
spermatids
spermatozoa
What 3 parts do sperm contain?
A head (contains genetic material and is covered with an acrosome) a midpiece (generates ATP from fructose and contains many mitochondia) and a flagellum (promotes motility)
Where are ova produced?
follicles in the ovaries
What is an oogonium?
divides to make a haploid ovum and polar bodies during oogenesis
What is the difference between a primary and secondary oocyte?
Primary = ova at birth -- arrested in prophase I Secondary = ovulated ovum -- arrested in metaphase II
What is the zona pellucida?
Made by glycoproteins and protects the oocyte & contains the compounds for sperm binding.
What is the corona radiata?
layer of cells adhered to the oocyte during ovulation
Where does Gonadotropin-releasing hormone (GnRH) come from?
The hypothalamus
What does GnRH cause?
The release of FSH and LH
What does FSH do in males?
stimulates the sertoli cells and triggers spermatogenesis
What does FSH do in females?
stimulates the development of the ovarian follicles
What does LH do in males?
causes the interstitial cells to produce testosterone
What is testosterone responsible for in males?
maintenance and development or the male reproductive system and male secondary sex characteristics
What does LH do in females?
LH causes ovulation
What happens in the follicular phase of the menstrual cycle?
GnRH secretion stimulates FSH and LH secretion, which promotes follicle development. Estrogen is also released.
What causes ovulation?
A sudden surge of LH, because at a certain threshold, estrogen starts having positive feedback
What happens in the luteal phase of ovulation?
LH promotes the ruptured follicle to become the corpus luteum, which secretes progesterone and estrogen, negative feedback on GnRH, LH and FSH
What happens with menstration?
Estrogen and progesterone levels fall and the endometrial lining sheds, the block on GnRH is removed.
What happens if fertilization does occur?
blastula produces human chorionic gonadotropic, which can maintain the corpus luteum
