Cell Cycle and Mitosis Flashcards
What phases make up interphase of cell cycle?
G1 S G2
What phase are cells that are not dividing in?
G0
Are chromosomes visible during interphase and why?
No because less condensed as chromatin
What organelles are created during G1?
Cells for energy and protein production
Mitochondria, ribsomes, ER
What happens during S phase?
Replication of genetic material - each chromosome will consist of two sister chromatids
What binds the two sister chromatids together?
Centromere
What happens during G2?
Check to make sure there enough organelles and that DNA was replicated properly
What is cytokinesis?
Split cytoplasm and organelles between daughter cells
Four phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
Which protein controls the checkpoint between G1 and S and what is it looking for?
p53 - looking that DNA is not damaged before it is replicated
What primary molecules are responsible for the cell cycle?
Cyclins and CDKs
What happens during prophase?
Condense chromatin into chromosomes
Centrioles go to opposite sides of the cell - create spindle fibers of microtubules
Nuclear membrane dissolves
Aster
Anchor the centrioles to the cell membrane
During which phase does the nuclear membrane dissolve?
Prophase
What happens during metaphase?
Kinectochore fibers interact with spindle apparatus to align the chromosomes at the metaphase plate
What happens during anaphase?
Centromeres split so each chromatid has its own - sister chromatids separate
Kinetochore fibers shorten to pull sister chromatids to opposite ends of the cell
What happens during telophase?
Reverse of prophase -
Spindle apparatus disappears
Nuclear membrane reforms
Chromosomes uncoil into chromatin
Why is meiosis I called reduction division?
Homologous chromosomes are separated into haploid daughter cells
Why is meiosis II called equatorial division?
Separation of sister chromatids
Mendel’s second law
Inheritance of one allele has no effect on the likelihood of inheriting another allele
When does crossing over occur?
Prophase I
Draw mitosis
Draw
Draw meiosis
Draw
Hemizygous
Males only have one X chromosome so they will express any sex-linked disorders
Carrier
Woman with one copy of a sex-linked disorder
What important gene does the Y chromosome have?
SRY gene - sex-determining gene that causes gonads to differentiate into testes
Where do sperm develop?
Seminiferous tubules
Where are the seminiferous tubules?
Testes
What are sertoli cells?
Nourish seminiferous tubules
What are male sex hormones as a group called?
Androgens
What secretes testosterone?
Cells of Leydig
Where are the testes located?
Scrotum
Where are sperm stored?
Epidiymis
What is the path of sperm during ejaculation?
Vas deferens – ejectulatory duct – urethra – penis
What nourishes sperm?
Seminal vesicles
What produces alkaline fluid for the sperm and why is it necessary?
Seminal vesicles and prostate gland, female reproductive tract is acidic
Bulbourethral glands
Produce clear fluid that cleans out urine and libricates urethra during sexual arousal
What is semen?
Sperm and seminal fluid
Which part of sperm contains genetic material?
Head
Acrosome
Modified golgi on the sperm head that allows for ovum penetration
Which part of sperm contains a lot of mitochondria?
Midpiece
Where are eggs produced?
Follicles
What hormone is released at the start of puberty?
Gonadotropin-releasing hormone (GnRH)
What releases GnRH?
Hypothalamus
What hormones are released as a results of GnRH?
Follicle stimulating hormone (FSH) Lutenizing hormone (LH)
What releases FSH and LH?
Anterior pituitary gland
How to FSH and LH interact in male sexual development?
FSH - stimulate sertoli cells and sperm maturation
LH - increase testosterone production
Male secondary sexual characteristics
Facial and axillary hair
Deep Voice
Increased muscle and bone mass
What do FSH and LH do in female sexual development?
FSH - estrogen secretion
LH - progesterone secretion from corpus luteum
What is the corpus luteum?
Remains of the ovarian follicle following ovulation - secretes progesterone
What is estrogen responsible for?
Development and maintenance of reproductive system, secondary sexual characteristics, and thickening of endometrium
What is progesterone responsible for?
Development and maintenance of endometrium but not initial thickening
Follicular phase events and hormone levels
Menstrual flow - GnRH increases which leads to increased production of FSH and LH to develop ovarian follicles
Ovulation events and hormone levels
Estrogen peaks and results in positive feedback, leading to GnRH FSH and LH spike - LH spike induces ovulation
Luteal phase events and hormone levels
LH causes the follicle to form the corpus luteum and secrete progesterone, which provides negative feedback on GnRH LH and FSH so only one egg ovulates
Menstruation
Progestone levels decline and lining is lost
Do estrogen and progesterone stimulate or inhibit GnRH?
Inhibit
hCG
Human chorionic gonadatropin - secreted if a blastocyst implants in uterine lining and is very similar to LH to maintain corpus luteum
What happens to hormone levels during menopause?
FSH and LH increase because negative feedback loop is removed
