Reproduction Flashcards
What is cell division?
the process by which a cell doubles its organelles and cytoplasm, replicates its DNA, and then divides in two.
When does Unicellular organisms use cell division
as a means of reproduction
When does multicellular organisms use cell division?
its a method of growth, development, and replacement of worn out cells.
What are the two types of cell division
mitosis and meiosis
Mitosis
the division and distribution of the somatic cells DNA to its two daughter cells in that both receives a complete copy of the original genome.
Karyokinesis
nuclear division
Cytokinesis
cell division
Karyo and Cyto kinesis in mitosis
Nuclear division is followed by cellular division.
How long does a cell spend in interphase?
90 percent of its life
what occurs in interphase
each chromosome is replicated so that during division, a complete copy of the genome can be distributed to both Daughter cells.
What happens to chromosomes after replication in interphase
they consist of sister chromatids held together at a central region called the centromere
Chromatin
uncoiled DNA
Chromosome
a single chromatid or the pair of chromatids attached at the centromere.
ploidy
the number of chromosome within the cells.
Diploid
2N This number in a single cell is due to the presence of homologous pairs of chromosomes made up of haploids
Haploid
N chromosomes that originate from the gamete cells of each parent.
Mitosis phases
prophase: chromosomes condense spindles form
metaphase: chromosomes align
anaphase: sister chromatids separate
telophase: new nuclear membranes form
Prophase
the initiation phase of mitosis the chromosomes condense and the centriole pairs (in animals) separate and move toward opposite sides poles of the cell.
spindle apparatus forms between them and the nuclear membrane dissolves, allowing spindle fibers to interact with the chromosome
Metaphase
during this phase of mitosis the centriole pairs are now at opposite poles of the cell
the fibers of the spindle apparatus attach to each chromatid at the centromere to align the chromosomes a the center of the cell forming the metaphase plate
Anaphase
The centromeres split so that each chromatid has its own distinct centromere allowing the chromatids to separate. the sister chromatids are pulled to opposite ends of the of the cell by the shortening of spindle fibers which consist of microtubules
Telophase
last phase of mitosis the spindle apparatus disappears and a nuclear membrane forms around the newly formed chromosomes. thus each contains the same number of chromosomes as the original parent. the chromosomes uncoil and resume their interphase form
Cytokinesis (phase)
near the end of telophase the cytoplasm divides into two daughter cells, each with a complete nucleus and its own set of organelles.
Cleavage furrow
in cytokinesis in animals when the cell membrane indents along the equator of the cell and finally pinches thorugh the cell separating the two nuclei
Cell plate
in plants it is an expanding partition that grows outward from the interior of the cell until it reaches the cell membrane during cytokinesis
Gametes
specialized sex cells produced by each parent
Meiosis
the process by which sex cells are produced for sexual reproduction. similar to mitosis other than it produces haploid cells halving the number of chromosomes and two divisions. resulting in 4 cells (gametes)
First meiotic division
preceded by interphase, first division produces two intermediate daughter cells with 2N chromosomes with sister chromatids.
Prophase I, Metaphase I Anaphase I, Telephase I
Prophase I
The chromatin condenses into chromosomes, spindle apparatus forms, the nucleoli and nuclear membrane disappear. Homologous chromosomes come together and initiate synapsis leading to recombination.
synapsis
Each chromosome consists of two sister chromatids, where the synaptic pair of homologus chromosomes contain for chromatids forming a tetrad.
Homologous chromosomes
chromosomes that code for the same traits, one inhereted from each parent.
chiasmata
when chromatids of homologous chromosomes connect and then break at corresponding points
crossing over
where homologous chromosomes exchange equivalent species of DNA at chiasmata during synapsis
Recombination
leads to increased genetic diversity within a species. Sister chromatids are no longer identical after recombination
Metaphase I
homologus pairs (tetrads) align at the equatorial plate and each pair attaches to a separate spindle fiber by its kinetochore.
Anaphase I
Homologous pairs separate and are pulled to opposite poles of the cell. called disjunctions. separated to the poles at random.
Disjunction
each chromosome of paternal origin separates form its homologue of maternal origin and either chromosome can end up in either daughter cell.
Telophase I
a nuclear membrane forms around each new nucleus. At this point each chromosome still consists of sister chromatids joined at the centromere. then they perform cytokenesis
Second meiotic division
Similar to miosis except that it is not preceded by chromosmal replication. the sister chromatids are split, move to opposite poles and are surronded by reformed nuclear membrane.
Gonads
specialized organs where gametes are produced, male- testes form sperm, female -ovaries form oocytes
Hermaphrodites
species that have both functional male and female gonads. includes the hydra and earthworm
Spermatogenesis
sperm production, begins at puberty that occurs in the seminiferous tubules. Dipliod cells called spermatogonia undergo mitosis to produce primary spermatocytes n undergo meiosis to produce four hapliod spermatids of equal size.
Sperm
(male gamete) mature sperm is an elongated cell with a head, tail, neck, and body. The head consists almost entirely of nucleus which contains the paternal genome. The tail is flagellum that propels the sperm and the neck has mitochondria to provide energy
Oogenesis
the production of female gametes, occurs in ovaries during embryonic development. One diploid oogonia divides by mitosis to produce primary oocyte cell that undergoes meiosis in the ovaries to produce a single mature egg.
polar body
which is a small cell that contains a little more than a nucleus. they rapidly degenerate after being produced by meiosis in oogeneis.
the mature ovum
is a large cell containing most of the cytoplasm, RNA organelles and nutrients needed by a developing embryo.
Fertilization
the union of the egg and sperm to form a zygote with a diploid number of chromosomes
External fertilization
occurs in vertebrates that reproduce in water (fish and amphibians). The female lays eggs in the water and the male deposits sperm in the vicinity. The lack of direct passage reduces chances
Internal fertilization
practiced by terrestrial vertebrates and provides a direct route for sperm to reach the egg cell. This increases the chances for fertilization and females produce fewer eggs.
Factors that effect egg production
the type of fertilization, if growth development occurs inside or out of the body, and parental care after birth is also related
Seven Up
path way of sperm: semeniferous tubules, epididymis, vas deferens, ejaculatory duct, urethra penis
Testes
located in an external pouch called the scrotum which are maintained at a temp 2-4 C below body temp. Where sperm is developed and testosterone.
Testosterone
male hormone that regulates secondary male sex characteristics including facial and pubic hair and voice changes.
Ovaries
found in the abdominal cavity, below the digestive system. The ovaries consist of thousands of follicles. the site of synthesizing and secretion of female sex hormones.
Female reproductive flow
Once a month an ovum is released from the ovary and drawn in by the oviduct and fallopian tube. each fallopain tube opens into the upper end of a muscular chamber called the uterus.
follicle
a multi layered sac of cells that contains, nourishes and protects an immature ovum. it is actually the follicle that contains, nourishes and protects an immature ovum. they also produce estrogen
uterus
a muscular chamber where the fetus is developed, the lower end of the uterus is the cervix
Cervix
connects with the vaginal canal, which is the site of sperm deposition during intercourse and where the baby is expelled during birth
estrogens
steroid hormones necessary for normal female maturation. They stimulate the development of the female reproductive systems and sexual characteristics and sex drive.
also responsible for the thickening of the endometrium. secreted by the follicles and the corpus luteum
Progesterone
a steroid hormone secreted by the corpus luteum during the luteal phase of the menstrual cycle. Stimulates the development and maintenance of the endometrial walls in preperation for implantation of the zygote.
The Menstrual cycle
Monthly cyclical pattern which can be divided into the follicular phase, ovulation, the luteal phase and menstruation
Follicular phase
begins with the cessation of the menstrual flow from the previous cycle. Reproductive hormones are at their lowest which shuts off negative feedback to the hypothalamus. This leads to the hypothalamus releaseing GnRH which stimulates FSH release from the anterior pituitary
GnRH
Gonadotropin releasing Hormone from hypothalamus
FSH
Follicle stimulating hormone, promotes the development of the follicle within the ovary which grows and begins to secrete estrogen
Ovulation
Midway through the cycle, a mature ovarian follicle bursts and releases an ovum that will be captured by the oviduct. Ovulation is caused by a surge in LH levels which is preceded and caused in part by a peak in estrogen levels created by the mature follicle.
Luteal phase
following ovulation LH induces the ruptured follicle to develop into the corpus luteum, which secretes estrogen and progesterone.
Progesterone function during luteal phase
causes the glands of the endometrium to mature and produce secretions that prepare the uterus for the implantation of an embryo.
Menstruation
if the ovum is not fertilized the corpus luteum atrophies. The resulting drop in progesterone and estrogen levels causes the endometrium to slough off giving rise to the menstrual flow
If fertilization occurs during the menstrual cycle..
the implanted embryo produces hCG which maintains the corpus luteum, which will secrete estrogen and progesterone to maintain endometrium
hCG
human chorionic gondadotrophin. maintians the corpus luteum and thus the supply of estrogen and progesterone sustains in the uterus until the placental embryo takes over production.
Life cycles of plants
characterized by an alternation of the diploid sporophyte generation and the haploid gametophyte generation. generally more plants have an increased dominance in sporophyte generations.
Gametophyte generation
the haploid gametophyte produces gametes by mitosis. The union of male and female gametes at fertilization restores the diploid sporophyte generation. Thus the gametes reproduce sexually while the sporophytes asexually. example is in mosses
Sporophtye generation
diploid sporophyte generation produces a haploid (monoploid) spore by meiosis. The spores divide by mitosis to produce the haploid or gametophyte generation. example are ferns
Angiosperms
flowering plants that have gametophytes consisting of a few cells that exsist for a short time. The woody plant that is seen is the sporophyte stage, the flower is the repro structure of angiosperms.
Stamens
the male organ of the flower and consists of a thin stalk like filament with a terminal sac called the anther.
Anther
produces haploid spores that develop into pollen grains
Pistil
the female organ of the flower consists of three parts:
Stigma, Style and Ovary
Stigma
the sticky part of the pistil that catches the pollen
Style
a tube-like structure connecting the stigma to the ovary at the base of the pistol
Ovary
the enlarged base of the pistil. It contains one or more ovules. Each ovule contains a monoploid egg nucleus.
Petals
specialized leaves surrounding and protecting the pistil. Their characteristic colors and odors attract insects which transfer pollen between plants and allow for fertilization.
Sepals
these are green leaves that cover and product the flower bud during early development.
Angiosperm Fertilization
The pollen grains are transferred from the anther to the stigma and the generative nucleus divides to form sperm nuclei which are the male gametes.
once the sperm nuclei enter the embryo sac one sperm nucleus fuses with the egg nucleus to form the diploid zygote which develops into the embryo.
the other sperm fuse with the endosperm which provides food to the embryo.
pollen grains
The pollen grain is the male gametophyte. the pollen grain contains a tube nucleus and a generative nucleus formed by mitosis of a microspore.
female gametophyte
develops in the ovule from one of four spores. this gametophyte is the embryo sac and contains nuclei including the two pair nuclei (endosperm) and an egg nucleus.
asexual reproduction
the production of offspring without fertilization. New organisms are formed by the division of a single parent cell.
Types: fission, budding, regeneration and parthogenesis. all plants use asexual in some form. some animal invertebrates.
Fission
simple form of reporduction seen in prokaryotes. the DNA replicates and a new plasma membrane and cell wall grow inward along the midline of the cell dividing it into two equally sized cells.
Where does fission occur
in one celled organisms such as amoebae, paramecia, algae and bacteria
Budding
the replication of a nucleus followed by unequal cytokinesis. The cell membrane pinches inward to form a new cell which is smaller in size but genetically identical to the parent cell. it will then grow to adult size.
where does budding occur
hydra and yeast
Regeneration
the regrowth of a lost or injured body part. Replacement of cells occurs by mitosis. Seen highly in starfish, salamanders and tadpoles. Must contain central disk
Parthogenisis
the development of an unfertilized egg into an adult organism. this process occurs naturally in certain lower organisms. Example worker bees and ants. Some can be induced by shock or prick like rabbit or frog eggs
Natural vegetative propagation
can occur as a natural means of plant reproduction. meristems provide a source of cells that can develop into an adult plant.
examples: bulbs, tubers, runners, rhizomes
Bulbs
split to form several bulbs as in tulips and daffodils
Tubers
are underground stems with buds, like the eyes of potatoes that can develop into adult plants
Runners
are stems running above and along the ground, extending from the main stem. can produce new roots and upright stems as they do in strawberry plans and lawn grasses
Rhizomes
are woods underground stems. they can develop new upright stems as they do in ferns and iris plants
Primary sex characteristics
Structures directly involved in reproduction. Ex, ovaries uterus and testes
Secondary sex characteristics
Characteristics that indicate sexual readiness or maturity Human features, like breasts and beards, muscle fat or manes in lions
Interstitial cells
Located in testes to produce hormones testosterone and androgens.
Seminiferous tubules
Located in testes and it is the production site of sperm
Epididymis
Coiled tube is the final site for maturation and storage of Sperm
Vas deferens
Transfers sperm from one epididymis to the urethra (where it exits)
Seminal vesicles
During ejaculation it secrets mucus(liquid medium) fructose (energy) and prostaglandins (stimulate uterine movement)
Prostate gland
Secretes milky fluid into urethra to neutralize acidity of urine that may be in urethra And acidity of vagina
Cowper’s glands
Secrete a liquid with an unknown function to urethra
Semen
The fluid containing sperm and secretions
Sperm head
Contains haploid nucleus with 23 chromosomes, tip is the acrosome which penetrates the egg
Midpeice and tail
The flagellum in 9+2 microarray mitochondria is Midpeice that surrounds flagella to provide apt and the tail propels
Follicle
Protects and nourished a developing (meiosis in menstrual cycle) primary oocytes
Secondary oocyte
Unequal cytokinesis occurs leaving more concentrated cytoplasm in one daughter cell after meiosis 1 during menstrual cycle to provide more nourishment for embryo
Polar bodies
Very little cytoplasm containing bodies. A daughter of primary oocyte that eventually disenergrates after meiosis 2
Ovulation
Release of secondary oocyte from follicle, and undergoes meiosis 2 if fertilized by sperm and second daughter cell a polar body
Sertoli cells
In seminiferous tubules provide nourishment to spermatids as they differentiate into mature sperm
LH in men
Aka ICSH (interstitial cells stimulating hormone) stimulates the interstitial cells to produce testosterone and androgen (constant)
FSH in men
Influences Sertoli cells promote the development of sperm
Amniotes
Extra embryonic membrane development including the chorion, allantois, amnion and yolk sac
Chorion
Outer membrane ( in birds and reptiles just gas exchange) in mammals it implants into the endometrium creating a placenta across this membrane gas and waste are exchanged
Allantois
Transfers waste from chorion in reptiles and becomes umbilical cord that transfers waste and nutrients between placenta and embryo
Amnion
Amniotic cavity that encloses a fluid filled cavity that cushions the embryo
Yolk sac
In reptiles and birds it digests the enclosed yolk to provide nutrients to embryo, empty in mammals due to the placenta
Archenteron
Center cavity formed by gastrulation and surrounded by endoderm cells, opening is blastopore
