Biology Ch 2. Reproduction Flashcards
(141 cards)
1
Q
Diploid
A
2n; cells have two copies of each chromosome
2
Q
Haploid
A
n; cells have one copy of each chromosome
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Q
Interphase
A
Includes G1, S, G2, DNA is uncoiled in the form of chromatin for ease of replication, longest part of the cell cycle
4
Q
G1 Stage
A
Presynthetic gap; cells create organelles for energy and protein production and increase their size, restriction point where DNA quality is checked occurs at the end of G1 before the cell can move on to S
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Q
S Stage
A
Synthesis; DNA is replicated and the chromatids are held together at the centromere
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Q
Chromatids
A
Each of the two chromosomal strands formed by DNA replication in the S phase of the cell cycle; held together by the centromere
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Q
G2 stage
A
Postsynthetic gap; further cell growth and replication of organelles in preparation for mitosis, another quality checkpoint at the end of this step
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Q
M stage
A
Mitosis; Mitosis and cytokinesis occur while DNA is tightly coiled in chromosomes to avoid losing any genetic material during cell division
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Q
G0 stage
A
Offshoot of G0 where cell performs its functions without preparing for division
10
Q
p53
A
Protein that plays role in two major checkpoints of the cell cycle
11
Q
Two major checkpoints of the cell cycle
A
G1 to S to determine if DNA quality is good enough for synthesis and G2 to M to ensure the cell has achieved adequate size and the organelles were properly replicated
12
Q
Cyclins
A
Concentration rises and falls during the cell cycle, bind to CDKs to phosphorylate and activate transcription factors for next stage of cell cycle
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Q
Cyclin-dependant kinases (CDK)
A
Concentration rises and falls during the cell cycle, cyclins bind to them to phosphorylate and activate transcription factors for next stage of the cell cycle
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Transcription factors mitosis
A
Promote transcription of genes required for the next cell cycles
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Q
Cancer
A
Occurs when the cell cycle becomes deranged, allowing damaged cells to undergo mitosis without regard to quality or quantity of the new cells produced, cancer cells may begin to product factors that allow them to delocalize and invade adjacent tissues elsewhere
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Q
Metastasis
A
Results from distant spread of cancerous cells throughout bloodstream or lymphatic systems
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Q
Mitosis
A
Produces two genetically identical diploid daughter cells from a single cell and occurs in somatic cells
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Q
Somatic cells
A
Perform mitosis to replicate, not involved in sexual reproduction
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Q
Mitosis phases
A
Prophase, metaphase, anaphase, telophase
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Q
Prophase
A
Chromatin condenses into chromosomes, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, spindle apparatus begins to form, spindle fibers contact each chromosomes kinetrochore
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Q
Metaphase
A
Chromosomes line up along the metaphase plate
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Q
Metaphase plate
A
aka equatorial plate, equidistant from two poles of the cell
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Q
Anaphase
A
Sister chromatids are separated and pulled to opposite poles when centromeres split into two and kinetochore fibers shorten
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Q
Telophase
A
Nuclear membrane reforms, spindle apparatus disappears, nucleoli reappear, cytokinesis occurs
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Cytokinesis
Cytosol and organelles are split between the two daughter cells
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Meiosis
Occurs in gametocytes and produces four nonidentical gametes, one round of replication and two rounds of division
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Gametocytes
Germ cells
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Gametes
Haploid sex cells
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Meiosis rounds of division
The reductional division and the equational division
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Meiosis I
Homologues come together, allow for crossing over, and then are separated from one another to result in haploid daughter cells, reductional division
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Homologues
Chromosomes that are given the same number but are of opposite parental origin
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Meiosis I steps
Prophase I, metaphase I, anaphase I, telophase I
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Prophase I
Chromatin condenses into chromosomes, spindle apparatus forms, nucleoli and nuclear membrane disappears, homologues come together and intertwine during synapsis to form tetrad crossing over occurs (accounts for mendels second law - independent assortment)
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Synapsis
Process where homologues come together and intertwine
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Tetrad
Four chromatids together
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Crossing over
When in a tetrad, genetic information is exchanged between one chromatid and its homologous chromosome
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Mendel's second law
aka law of independent assortment - crossing over accounts for it, states that inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes
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Metaphase I
Homologous pairs (tetrads) line up on opposite sides of the metaphase plate when each pair is attached to a separated spindle fiber by its kinetochore
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Anaphase I
Homologous chromosomes are pulled to opposite poles of the cell (accounts for mendels first law - segregation_
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Mendels first law
aka law of segregation - anaphase I accounts for it, the distribution of homologies chromosomes to each intermediate daughter cell is random with respect to parental origin
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Telophase I
Nuclear membrane reforms, chromosomes may or may not fully decondense and cell may enter interkinesis after cytokinesis
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Interkinesis
Short rest period during which the chromosomes partially uncoil
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Meiosis II
Sister chromatids are separated from each other in a process that is functionally identical to mitosis, equational division, no change in ploidy
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Sister chromatids
Copies of the same DNA held together at the centromere
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Cell cycle
A specific series of phases during which a cell grows, synthesizes DNA, and divides
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Cell cycle stages
G1, S, G2, M
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Chromatin
Less condensed form of DNA present during interphase
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Centriole
A small organelle in the cytoplasm of animal cells; organizes the spindle apparatus during mitosis and meiosis
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Centrosomes
Paired cylindrical organelles located in the cytoplasm that contain the centrioles, microtubule organizing center
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Centromere
The area of a chromosome where sister chromatids are joined; also the point of attachment to the spinal fiber during mitosis and meiosis
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Spindle fibers
Made of microtubules, radiate outward from the centrioles
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Asters
Formed by some microtubules that anchor the centrioles to the cell membrane
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Kinetochore fibers
Spindle fibers that extend towards middle of the cell, attached to kinetochores
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Kinetochores
Protein striations at the centrosome that serve as attachment points for kinetochore fibers
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Spindle apparatus
A structure within dividing cells composed of microtubules; it is involved in the separation of chromosomes during mitosis and meiosis
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Synaptonemal complex
Group of proteins that holds homologous chromosomes together
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Recombination
Can occur during crossing over, increases variety of genetic combinations, unlinks linkages
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Chiasma
Contact between homologous chromosomes where chromatids may break and DNA can be exchanged
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Linkage
The tendency for genes to be inherited together
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Disjunction
Process where homologous pairs separate and are pulled to opposite poles of the cell
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Meiosis II steps
Prophase II, metaphase II, anaphase II, telophase II
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Biological sex
Determined by 23rd chromosome (XX- female, XY-male)
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X chromosome
Carries a sizable amount of genetic information; mutations of X-linked genes can cause sex-linked disorders
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Hemizygous
Meaning only one copy of the gene is present, ex. males for X chromosome, important for sex-linked genes and means they will display trait even if they only have one recessive allele
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Carriers
Contain one copy of affected allele but do not exhibit disease, ex. women in the case of sex-linked genes
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Y chromosome
Carries little genetic information, but does contain the SRY gene
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SRY gene
Sex-determining region Y gene that causes gonads to differentiate into testes
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Sperm
Develop in the seminiferous tubules in the testes, are nourished by Sertoli cells, carry either the X or Y chromosome, only contribute DNA to zygote
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Seminiferous tubules
Where sperm develop, are highly coiled
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Testes
Contain to functional components - the seminiferous tubules and the interstitial cells of Leydig, located in scrotum
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Interstitial cells of Leydig
Cells in the testes that secrete testosterone
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Testosterone
Male sex hormone that is responsible for the maintenance and development of the male reproductive system and the male secondary sex characteristics, released by interstitial cells of Leydig in the testes
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Androgens
Male sex hormone
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Scrotum
Hangs outside the abdominal cavity and has a temperature of 2 to 4 degrees Celsius lower than the rest of the body
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Epididymis
Where sperm gain motility via their flagella and are stored until ejaculation
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Ejaculation
Sperm travel through the vas deferrers to the ejaculatory duct, and then through the urethra and out through the penis
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Vas deferens
What sperm travel through to get from epididymis to ejaculatory duct
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Ejaculatory duct
Duct at the posterior edge of the prostate gland, the two ejaculatory ducts fuse to form the urethra
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Urethra
Formed by two fused ejaculatory ducts, carries sperm through the penis as they exit the body
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Seminal vesicles
Contribute fructose to nourish sperm and produce alkaline fluid
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Prostate gland
Produces alkaline fluid
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Bulbourethral glands
Produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
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Semen
Composed of sperm and seminal fluid
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Seminal fluid
Produced through a combined effort by the seminal vesicles, prostate gland, and bulbourethral glands, include fructose, alkaline fluid, and the clear viscous fluid for cleaning/lubrication
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Spermatogenesis
Four haploid sperm are produced from a spermatogonium via meiosis, occurs in seminiferous tubules
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Primary spermatocytes
Diploid sperm germ cells after S stage
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Secondary spermatocytes
Haploid sperm germ cells after meiosis I
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Spermatids
Haploid sperm germ cells after meiosis II
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Spermatozoa
Sperm germ cells after maturation
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Sperm parts
Head, midpiece, and flagellum
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Sperm head
Contains genetic material and is covered in an acrosome
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Acrosome
A modified Golgi apparatus that contains enzymes that help the sperm fuse with and penetrate the ovum
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Sperm midpiece
Generates ATP from fructose and contains many mitochondria
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Sperm flagellum
Promotes motility
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Ova
Eggs that are produced in follicles in the ovaries, carry only the X chromosome
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Follicles
Multilayered sacs that contain, nourish and protect immature ova
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Ovaries
The female egg-producing gonad, also produce estrogen and progesterone, located in pelvic cavity and consist of thousands of follicles
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Ovulation
Occurs once each month when an egg is sent into the peritoneal sac then into the fallopian tube, stimulated by a sudden surge in LH that is triggered when estrogen levels reach a threshold and switch from negative to positive feedback effects, GnRH and FSH levels also spike
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Peritoneal sac
Where an egg is drawn into at the beginning of ovulation, lines the abdominal cavity
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Fallopian tube
aka oviduct - Connect the peritoneal sac to the uterus, is lined with cilia to pull the egg from the peritoneal sac and propel the egg forward
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Uterus
Contains the cervix, connected to fallopian tubes, site of fetal development
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Cervix
Lower end of the uterus, on top of the vaginal canal
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Vaginal canal
Below the cervix, site of natural childbirth
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Vulva
External female anatomy
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Oogenesis
Process in which one haploid ovum and a variable number of polar bodies are formed from an oogonium, this is because cytokinesis is uneven
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Oogonium
Female diploid stem cells
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Primary oocytes
Status of oogonia at birth, they have already undergone replicated (S stage completed) and are arrested in prophase I, diploid still
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Secondary oocytes
Status of an ovulated egg each month, they are arrested in metaphase II, haploid
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True mature ovum
An oocyte that is fertilized, meaning it has completed meiosis II because fertilization is necessary for that, contributes everything to a zygote (DNA, organelles, cytoplasm)
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Polar body
Cells that receive very little cytoplasm and organelles during the uneven cytokinesis of oogenesis
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Zona pellucida
An acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding
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Oocyte
An undifferentiated cell that undergoes meiosis to produce an ovum, surrounded by two layers: the corona radiate and the zone pellucid
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Corona radiata
A layer of cells that is adhered to the oocyte during ovulation, outside the zone pellucida
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Gonadotropin-releasing hormone
GnRH - hormone from hypothalamus that causes the release of follicle-stimulating hormone and luteinizing hormone, functions of these hormones depends on the sex of the individual
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Follicle stimulating hormone in males
Hormone that is released because of Gonadotropin releasing hormone, in males it stimulates the Sertoli cells and triggers spermatogenesis
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Luteinizing hormone in males
Hormone that is released because of gonadotropin releasing hormone, in males causes the interstitial cells to produce testosterone
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Follicle stimulating hormone in females
Hormone that is released because of gonadotropin releasing hormone, in females stimulates the development of the ovarian follicles, stimulate production of estrogen and progesterone
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Luteinizing hormone in females
Hormone that is released because of gonadotropin releasing hormone, in females causes ovulation, stimulates production of estrogen and progesterone
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Menstrual cycle
Periodic growth and shedding of the endometrial lining
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Follicular phase
Low levels of estrogen and progesterone cause GnRH secretion which stimulates FSH and LH secretion, these promotes follicle development, estrogen is releases (which via negative feedback causes FSH and LH to level off), stimulating regrowth of endometrial lining and vascularization and glandularization of the decidua, begins with the menstrual flow (shedding of the previous cycles uterine wall) begins
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Decidua
Layer of the endometrium
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Estrogen
Secreted in response to FSH and result in the development and maintenance of the female reproductive system and female secondary sexual characteristics, stimulates development of reproductive tract in the embryo, thickens the endometrium each month as an adult
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Luteal phase
LH causes the ruptured follicle to become the corpus luteum which secretes progesterone, high estrogen and progesterone levels cause negative feedback on GnRH, FSH, and LH which prevents ovulation of multiple eggs
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Progesterone
Maintains the uterine lining, secreted by the corpus luteum or placenta, does not aid in initial thickening of uterine lining
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Menstruation
Occurs if no fertilization happens, as estrogen and progesterone levels drop, the endometrial lining is sloughed off, and the block on GnRH production is removed so next cycle begins
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Human chorionic gonadotropin
hCG - is produced by the blastula if fertilization occurs, is an LH analog, maintains the corpus luteum, levels drop at the end of the first trimester as the placenta takes over progesterone production
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Menopause
Occurs when the ovaries stop producing estrogen and progesterone between ages 45 and 55 as they get less sensitive to FSH and LH, menstruation stops and FSH and LH feels rise, physical and physiological changes include flushing, hot flashes, bloating, headaches, and irritability
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Sex-linked disorder
Linked to the x chromosome, men more likely to get it because they only need one copy of the recessive X linked allele whereas women would need two recessive alleles
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Sertoli cells
Nourish sperm in seminiferous tubules
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Spermatogonium
Male diploid stem cells
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Meiosis I oogenesis
Results in one haploid secondary oocyte and a polar body
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Meiosis II oogenesis
Only completes when sperm penetrates zone pellucid and corona radiate with the help of acrosomal enzymes, results in a mature ovum and another polar body
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Zygote
Diploid cell the results from the pronuclei of the sperm and the ovum
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Puberty hypothalamus
Prior to puberty, no GnRH released, restriction lifted at the start of puberty
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Anterior pituitary gland
Synthesizes and releases FSH and LH as a response to GnRH
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Male secondary sexual characteristics
Facial and axillae hair, deepening of the voice, increased bone and muscle mass
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Female secondary sexual characteristics
Breast growth, widening of the hips, changes in fat distribution
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Endometrium
Lining of the uterus
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Corpus luteum
Secretes progesterone, is the remains of the ovarian follicle following ovulation
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Events of menstural cycle
Follicular pase, ovulation, luteal phase, menstuation
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Pregnancy
If fertilization does occur, zygote will develop into blastocyst that will implant in the uterine lining and secrete hCG, GnRH production remains low because high progesterone and estrogen
