CALM 3 Flashcards
an ordered series of events involving cell growth and cell division that produces two new daughter cells.
cell cycle
In eukaryotic cells, the stages of the cell cycle are divided into two major phases:
Interphase and the mitotic (M) phase.
During ____ , the cell grows and makes a œpy of its DNA.
interphase
During the _____phase, the cell separates its DNA into two sets and divides its cytoplasm, forming two new cells.
mitotic {M}
cell undergoes normal growth processes while also preparing Ibr cell division.
interphase
The three stages of interphase are called
G1, S & G2
also called the first gap phase, the cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps.
G1
the cell synthesizes a complete copy of the DNA in its nucleus.
s phase
microtubule-organizing structure
centrosome
It also duplicates a microtubule-organizing structure called the centrosome.
s phase
the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis.
G2
ends when mitosis begins.
G2 phase
a type of cell division in which one cell (the mother) divides to produce two new cells (the daughters) that are genetically identical to itself.
Mitosis
part of the division process in which the DNA of the cell’s nucleus is split into two equal sets of chromosomes.
mitosis
Condensed chromosomes take up stains. The spindle assembles, centrioles appear and the nuclear envelope breaks down,
prphase
Chromosomes are uncondensed.
Presence of Nucleus and Nucleus.
interphase
Chromosomes align
metaphase
Centromeres part and chromatids separate
anaphase
The spindle disassembles and the nuclear envelope re-forms
telophase
has no partition
anaphase
Sperm and oocytes are ____ or sex cells.
gametes,
Paired structures , called ___ where the sperm and oocytes are manufactured;
gonads
Are manufactured in the seminiferous tubules, which wind tightly within the testes, which descend into the scrotum.
Sperm cells
dd secretions to the sperm cells to form seminal fluid.
prostate gland, seminal vesicles, and bulbourethral glands
pleasurable sensation
orgasm
discharge of sperm from the penis
ejaculation
The discharge of sperm from the penis, called ejaculation, delivers about ___sperm cells.
200 to 600 million
Once a month after puberty, an ovary releases ___, which is drawn into a nearby uterine tube.
one oocyte
If a sperm fertilizes the oocyte in the uterine tube, the fertilized____ continues into the uterus, where for nine months it divides and develops.
ovum
form from special cells, called germline cells, in a type of cell division called meiosis that halves the chromosome number.
gametes
Gametes contain
23 different chromosomes
The first division is called a reduction division
meiosis I
equational division
meiosis II
it reduces the number of replicated chromosomes from 46 to 23.
meiosis I
Produces four cells from the two cells formed in the first division by splitting the replicated chromosomes.
meiosis II
Replicated chromosomes condense and become visible when stained.
PROPHASE I (EARLY)
At this time, the homologs exchange parts in a process called __-
crossing over.
Crossing over mixes up paternally and maternally derived genes on ___ _of chromosomes.
homologous pairs
Toward the end of Prophase I, chromosomes condense, becoming visible.
Spindle forms.
Nuclear envelope fragments.
Spindle fibers attach to each chromosome.
PROPHASE I (LATE)
Paired homologous chromosomes align along the equator of the cell.
Each member of a homologous pair attaches to a spindle fiber at opposite poles.
METAPHASE I
Homologous chromosomes separate to opposite poles of the cell.
ANAPHASE I
Nuclear envelopes partially assemble around chromosomes. Spindle disappears. Cytokinesis divides cells into two.
TELOPHASE I
Prophase II marks the start of the second meiotic division.
Nuclear envelope fragments.
Spindle forms and fibers attach to both chromosomes.
PROPHASE II
Chromosomes align along the equator of the cell.
METAPHASE II
The centromeres part, and the newly formed chromosomes, each now in the unreplicated form, move to opposite poles.
ANAPHASE II
In this stage, nuclear envelopes assemble around two daughter nuclei.
Chromosomes decondense.
Spindle disappears.
Cytokinesis divides cells.
TELOPHASE II
The net result of meiosis is
four haploid cells
The production of sperm (spermatogenesis) and eggs (oogenesis),
Spermatogenesis
Takes place through the process of meiosis.
Spermatogenesis
These stem cells, called, _____ go through mitosis with one offspring going on to differentiate into a sperm cell, while the other gives rise to the next generation of sperm.
spermatogonia (singular: spermatogonia)
only operates in the testes area, not the penis.
vasectomy
A ____can’t be conceived because it can’t penetrate the wall of the egg.
lollipop shaped head
In meiosis I, each primary spermatocyte halves its genetic material to form
two secondary spermatocytes.
In meiosis II, each secondary spermatocyte divides, yielding ___by bridges of cytoplasm. Maturing spermatids separate and shed some cytoplasm.
two equal-sized spermatids attached
has built-in protections that help prevent sperm from causing some birth defects.
Meiosis in the male
Dutch histologist ___ presents a once-popular hypothesis that a sperm carries a preformed human called a ___
Niklass Hartsoeker ; homunculus.
egg making
oogenesis
Unlike male cells, oogonia are not attached. Instead, ___surround each oogonium.
follicle cells
As each oogonium grows,
cytoplasm accumulates, DNA replicates, and the cell becomes a primary oocyte.
First menstruation
menarche
depends on the number of eggs you have produced and it is also a factor if you have a regular or irregular menstruation.
menopausal
After puberty, the most mature oocyte in one ovary bursts out each month, in an event called
___
ovulation.
Happens primarily in the ovaries because of the accumulation of the developing follicles (potentially mature or immature egg cells) that are stuck and are not released in the ovaries.
PCOS Polycystic ovary syndrome
Are 1 or 2 follicles that are expanding and consist of the simple fluids.
Follicular Cyst
accumulates cytoplasm and replicates its DNA, becoming a primary oocyte.
oogonium
the primary oocyte divides, forming a small polar body and a large, haploid secondary oocyte.
meoisis
the secondary oocyte divides, yielding another small polar body and a mature haploid ovum
meiosis ii
A prenatal human is considered an ____. During this time, rudiments of all body parts form.
embryo for the first 8 weeks
The embryo in the first week is considered to be in a ____because it has not yet settled into the uterine lining.
“preimplantation” stage
Prenatal development after the eighth week is the____when structures grow and specialize.
fetal period
From the start of the ninth week until birth, the prenatal human organism is a
fetus
A sperm cell can survive in the woman’s body for up to
3 days
oocyte can only be fertilized in the ___ hours after ovulation.
12 to 24
A process in the female called ____chemically activates sperm, and the oocyte secretes a chemical that attracts sperm.
capacitation
Before fertilization occurs, the sperm’s acrosome ___ , spilling enzymes that help the sperm’s nucleus enter the oocyte.
burts
A sperm first contacts a covering of follicle cells, called the ___ that guards a secondary oocyte
corona radiata
begins when the outer membranes of the sperm and secondary oocyte meet.
Fertilization, or conception
Usually only the sperm’s head enters the oocyte. Within___hours of the sperm’s penetration, the ovum’s nuclear membrane disappears, and the two sets of chromosomes, called , ___approach one another.
12 pronuclei
fertilized ovum is called a
zygote.
From ovulation to implantation.
Cleavage
forms in the uterine tube when a sperm nucleus fuses with the nucleus of an oocyte.
zygote
The first division proceeds while the zygote moves toward the
uterus.
By day 7 , the zygote, now called a ___, begins to implant in the uterine lining.
blastocyst
About a day after fertilization, the zygote divides by mitosis, beginning a period of frequent cell division called
cleavage
resulting early cells
blastomeres
When the blastomeres form a solid ball of sixteen or more cells, the embryo is called a
morula
cells form a clump on the inside lining
inner cell mass
A week after conception, the blastocyst begins to nestle into the woman’s uterine lining (endometrium). This event, called___ takes about a week.
implantation
During the second week of prenatal development,
A space called ____ the forms between the inner cell mass and the outer cells anchored to the uterine lining.
amniotic cavity
layer nearest the amniotic cavity is the
ectoderm
inner layer, closer to the blastocyst cavity, is the
endoderm
Shortly after, a third layer, the ___ , forms in the middle.
mesoderm
three-layered structure
primordial embryo, or the gastrula.
Once these three layers, called ___, form, many cells become “determined” or fated, to develop as a specific cell type.
primary germ layers
First to develop and continue until birth.
Central Nervous system
Last to develop.
Respiratory and the Digestive system
By the third week after conception, finger-like outgrowths called ____ extend from the area of the embryonic disc close to the uterine wall, and these project into pools of the woman’s blood.
chorionic villi
By ____, the placenta is fully formed.
10 weeks
manufactures blood cells,
yolk sac
a membrane surrounding the embryo that gives rise to the umbilical blood vessels.
allantois
Twins result when two sperm fertilize two oocytes.
Fraternal or dizygotic (DZ)
are no more alike than any two siblings, although they share a very early environment in the uterus.
DZ twins
Twins descend from a single fertilized ovum and therefore are genetically identical.
Identical, or monozygotic (MZ),
About a third of all MZ twins have completely separate
chorions and amnions.
About two-thirds share a chorion but have separate
amnions.
Slightly fewer than 1 percent of MZ twins .
share both amnion and chorion
In a process called ____ , the specialization of one group of cells causes adjacent groups of cells to specialize.
embryonic induction
Transformation of the simple three layers of the embryo into distinct organs.
organogenesis
During the third week of prenatal development, a band called the___________ appears along the back of the embryo.
primitive streak
gradually elongates to form an axis that other structures organize around as they develop.
primitive streak
eventually gives rise to connective tissue progenitor cells and the notochord, which is a structure that forms the basic framework of the skeleton.
primitive streak
Appearance of the ___ marks the beginning of organ development.
neural tube
heart begins to beat around day______ , and this is easily detectable by day __
18 ;22
_______ is one of spectacularly rapid growth and differentiation.
fourth week of embryonic existence
Arms and legs begin to extend from small buds on the torso.
Blood cells form and fill primitive blood vessels.
Immature lungs and kidneys begin to develop.
fourth week of embryonic existence
By_____, the embryo’s head appears to be too large for the rest of its body.
fifth and sixth weeks,
By the___ , a skeleton composed of cartilage forms.
seventh and eighth weeks
Differences may be noticeable on ultrasound scans by
12 to 15 weeks.
By____, the fetus sucks its thumb, kicks, makes fists and faces, and has the beginnings of teeth.
week 12
By the ____, the fetus has hair, eyebrows, lashes, nipples, and nails.
fourth month
By ____the vocal cords have formed, but the fetus makes no sound because it doesn’t breathe air.
18 weeks,
By the ____, the fetus curls into a head-to-knees position.
end of the fifth month,
During the_____ , the skin appears wrinkled because there isn’t much fat beneath it, and turns pink as capillaries fill with blood.
sixth month
By the end of the ____, the woman feels distinct kicks and jabs and may even detect a fetal hiccup.
end of second trimester
In the ___, fetal brain cells rapidly link into networks as organs elaborate and grow.
final trimester
Approximately____ after a single sperm burrowed its way into an oocyte, a baby is ready to be born.
266 days
The time when genetic abnormalities, toxic substances, or viruses can alter a specific structure is its
critical period.
Chemicals or other agents that cause birth defects
teratogens (Greek for “monster-causing”).
A mild tranquilizer to alleviate nausea early in pregnancy, during the critical period for limb formation.
Thalidomide
vmay slow fetal growth, particularly of the head, but the babies quickly catch up.
Cocaine
___crosses the placenta and prevents the fetus’s hemoglobin molecules from adequately binding oxygen.
Carbon monoxide
A child with FAS has a characteristic
small head and a flat face.
Intellectual impairment ranges from minor learning disabilities to mental retardation.
FAS
a vitamin A derivative that causes spontaneous abortion and defects of the heart, nervous system, and face in exposed embryos.
acne medicine isotretinoin (Accutane)
Viruses are small enough to cross the placenta and reach a fetus.
Viral infection
is a well-known viral teratogen.
German measles (rubella)
can harm a fetus or newborn whose immune system is immature.
Herpes simplex virus
These babies are healthy, but at high risk for developing serious liver problems as adults.
hepatitis B infection
means moving through the life cycle.
aging
have too little muscle tissue, and since muscle is the primary site of insulin action, glucose metabolism is altered.
Growth-retarded babies
Cysts that may have been present but undetected in the kidneys during one’s twenties begin causing bloody urine, high blood pressure, and abdominal pain in the thirties.
polycystic kidney disease
The uncontrollable movements, unsteady gait, and diminishing mental faculties of ____typically become obvious near age 40, but may have begun years earlier.
Huntington disease
The brains of Alzheimer disease patients contain deposits of a protein called ____in learning and memory centers.
beta amyloid
Alzheimer brains also contain structures called ____, which consist of a protein called ___
neurofibrillary tangles; tau
most severe rapid aging disorders are the segmental progeroid syndromes
progeria
