genetics
CYTOKINESIS?
Organelles & macromolecules are distributed b/t the 2 daughter cells. -finally, the microFILAMENT band contracts like a draw-string, separating the newly formed cells.
During wk 3, Chorionic villi extend toward the maternal circulation, & the __________begins to form?
PLACENTA
OTHER stem cells & progenitor cells are?
PLURIPOTENT: Daughter cells have fewer possible fates (college freshman considering of many majors) **some are Multipotent: daughter cells have only a few "developmental" choices (college junior's more narrowed focus in selecting courses)
what are the other products of meiosis?
POLAR BODIES, contain the other 3 sets of chromosomes & normally degenerate
where do female's millions of oocytes arrest?
PROPHASE 1
mitochondria
PROVIDE ENERGY by breaking the chemical bonds that hold together the nutrient molecules in food -outer membrane & inner membrane that forms folds called CRISTAE(folds hold enzymes that catalyze biochemical rxns that release energy from nutrient molecules)---> freed energy is captured and stored in the bonds that hold ATP!!!
ANAPHASE?
Plasma membrane indents at the center, where the metaphase chromosome line up. -band of microFILAMENTS forms on the inside face of the plasma membrane, constricting the cell down the middle. -centromeres part-->relieves tension & releases 1 chromatid from each pair to move to opposite ends of the cell. -microtubule movements stretch the dividing cell. -CELL TEMPORARILY CONTAINS TWICE THE NORMAL # OF CHROMOSOMES BC EACH CHROMATID BECOMES AN INDEPENDENTLY MOVING CHROMOSOME, BUT THE CELL HAS NOT PHYSICALLY DIVIDED.
as implantation starts, the trophoblast secrete the "pregnancy hormone" (hCG), WHICH?
Prevents menstruation, hCG detected in a woman's urine or blood is 1 sign of pregnancy
MEIOTIC division in OOGENESIS???
Produces cells of DIFFERENT SIZES (unlike male pathway)
when are Ova (eggs) made?
Prophase 1, shortly after SYNAPSIS (why radiation doses are lower for women)
insertional translocation
Rare; part of 1 chromosome inserts into a nonhomologous chromosome. -symptoms may occur if a vital gene is disrupted of if genetic material is lost of present in excess
apoptosis is a continuous process that begins when?
"death receptor" on the cell's plasma membrane receives a signal to die. -w/in seconds, enzymes called CASPASES are activated inside the doomed cell, stimulating each other & snipping apart various cell components
ADULT stem cells (naturally occurring)?
"tissue specific or somatic stem cells" -found in tissues of fetuses, embryos, children, & not just in adult bodies -SELF-RENEW but most are MULTIPOTENT(most specialized daughter cells)
HOW MANY GROUPS ARE THERE?
(7) A, B, C, D, E, F, G
acrosome?
(membrane-covered area on the front end) -contains enzymes that help the sperm cell penetrate the protective layers around the oocyte
dicentric?
(paracentric) abnormal chromosome w. 2 centromeres
acentric?
(paracentric) crossover w/in an inversion loop is a small piece that lacks a centromere;;; when a cell divides, the fragment is lost bc a centromeres is required for cell division
shorthand karyotype:
-# of chromosomes -gender -change/abnormal
Spermatogonia divide miotically, yielding:
-1 stem cell & 1 cell that accumulates cytoplasm & becomes a PRIMARY SPERMATOCYTE
a stem cell divides by mitosis to yield either 2 daughter cells that are stem cells like itself, or?
-1 that is a stem cell & 1 that is partially specialized progenitor cell
In meiosis 2, each 2^ spermatocyte divides, yielding:
-2 equal-sized spermatids attached by bridges of cytoplasm. -maturing spermatids separate & Shed some cytoplasm
interphase consists of _____phases, where? ----phase, where?
-2 gap (G) Phases: when proteins & lipids are produced -synthesis phase: when DNA is replicated
metaphase 2
-DYADS align down the center of the cell
-----Packages secretions into vesicles, which exit through the plasma membrane?
-Golgi apparatus
chromosome microarray analysis (fetal cell sorting)
-SAFEST; but still experimental -researchers can detect fetal cells, DNA, or mRNA in a sample of blood from a pregnant woman -fetal cells from either sex can be distinguished from maternal cells using a fluorescence-activated cell sorter (it separates fetal cells from maternal blood by identifying surface characteristics that differ from those on the woman's cells
METAPHASE1
-TETRADS align along the equator of the cell. -each member of a tetrad attaches to spindle fibers at OPPOSITE POLES-->genetic diversity ;;maternal/paternal doesn't have a specific pole -random alignment=INDEPENDENT ASSORTMENT
What enables the cell to become destined & a fertilized ovum to accumulate most of the cytoplasm & organelles from the 1^ oocyte, but w. ONLY 1 genome copy??
-Unequal division & apportioning of cell parts
when do differences of sexes start to appear? what happens in the final trimester?
-after wk 6 -fetal brain cells rapidly link into networks as organs elaborate & grow; fat forms beneath skin; ***digestive/resp. develop last
the notochord induces a sheet of overlying ectoderm to fold into the HOLLOW NEURAL TUBE, which develops?
-brain & spinal cord
anaphase 2?
-centromeres part, & the newly formed MONADS(separated DYADS) each now are in the UNreplicated form, move to OPPOSITE poles
what happens in nondisjunction?
-chromosome pair fails to separate at anaphase of either the 1st of 2nd meiotic division. -produces a sperm/oocyte that has 2 copies of a particular chromosome, or none, rather than 1 normal copy **zygote has either 45 or 47 chromosomes
PROPHASE 1 begins as the replicated chromosomes?
-condense & become visible when stained -spindle forms; nuclear envelope fragments -(middle)homologs line up next to one another, gene by gene, in an event called SYNPASIS produces a BIVALENT(on top of each other???) -a mixture of RNA& protein holds the chromosome pairs together. -at this time, the homologs exchange parts, or CROSS OVER ***now NEW GENE COMBOS ARISE*** -(End) synapsed chromosomes(4 TETRADS) separate but remain attached at a few points along their lengths.
CASPASE or killer enzymes?
-destroy enzymes that replicate & repair DNA -activate enzymes that cut DNA into similarly sized small pieces -tear apart the cytoskeleton, including threads that support the nucleus, which collapses, condensing the DNA within -cause mitochondria to release molecules that trigger further caspase activity, end the cell's energy supply, & destroy these organelles -abolish the cell's ability to adhere to other cells -send a certain phospholipid from the plasma membrane's inner face to its outer surface, where it attracts phagocytes that dismantle the cell remnants
what is translocation?
-different chromosomes exchange or combine parts -can be inherited bc can be carriers
cytokinesis 2
-divides cell "potential Gametes"-->23 chromosomes & 23 gonads w/ 1 piece of DNA, ready to reproduce
3 general stem cell sources?
-embryonic stem (ES) cells -induced pluripotent stem (iPS) Cells -adult stem cells
seminal vesicles?
-energy for sperm, hormone;; -secretes fructose (energy-rich sugar) and hormone-like prostanglandins, which may stimulate contractions in the female that help sperm & oocyte meet.
chrionic villus sampling?
-examines chromosomes from cells snipped off the chorionic villi; villi cells & embryonic cells come from same fertilized ovum
Cleavage: ovulation to implantation ---------------------------------------------- zygote forms in the uterine tube when a sperm nucleus? the 1st divisions proceed while the zygote moves toward..? by day 7, the zygote (now blastocyst) begins?
-fuses w/the nucleus of an oocyte ....Uterus -to implant in the uterine lining
what does the primitive streak do?
-gradually elongates to form an axis that other structures organize around as they develop
what does telomeres determine?
-how many more mitoses will occur!! -Crowding, hormones, and growth factors signal cells from the outside; the interactions of cyclins & kinases trigger mitosis from inside
embryonic stem cells?
-made from inner cell mass from a region of very early embryo but through a laboratory dish -some become PLURIPOTENT & can self-renew a.)"left-over" embyros from fertility clinics b.) nuclear transfer aka Cloning--copies the nucleus donor's genome **human ES cells are still the gold-standard bc they moer closely approximate normal development than do iPS cells
s phase
-many proteins are synthesized during this phase, including those the form the mitotic SPINDLE that will pull apart the chromosomes. -microtubules form structures called CENTRIOLES near the nucleus. -centriole microtubules join w other proteins and are oriented at rt angles to each other, forming paired, oblong structures called CENTROSOMES that organize other microtubules into the spindle
meiosis (book)
-meiosis is a form of cell division in which certain cells are set aside and give rise to haploid gametes -in actuality, the 1st meiotic division reduces the # of chromosomes to 23, all in the replicated form. -in the 2nd meiotic division, the cells essentially undergo mitosis; the result of 2 meiotic divisions is 4 HAPLOID cells.
allantois
-membrane surrounding the embryo that gives rise to the umbilical blood vessels (umbilical chord forms around these blood vessels and attaches to the center of the placenta)
meiosis does what?
-mixes up trait combinations ***EXPLAINS WHY SIBLINGS DIFFER GENETICALLY FROM EACH OTHER & FROM PARENTS********** -also provides genetic diversity---different genotypes & phenotypes(evolution by natural selection)
UPD can be caused from? **Rare**
-nondisjunction occurs in a sperm & oocyte that join, a pair of chromosomes (or their parts) can come solely from 1 parent, rather than 1 from each parent. -trisomic embryo in which some cells lose the extra chromosome, leaving 2 homologs from 1 parent
prophase 2 marks? (start of 2nd meiotic division)
-nuclear envelope fragments. -Spindle forms & fibers attach to both DYADS -DYADS condense & become visible
telophase 2?
-nuclear envelopes assemble around (the 4 Nuclei, which then separate into individual cells) 2 daughter nuclei. -MONADS decondense; spindle disappears -net result: 4 HAPLOID CELLS, each carrying a NEW ASSORTMENT OF GENES & chromosomes that represent a single copy of the genome
how is a chromosome spread made/done? --karyotyping
-obtain cells -culture -cell cycle-Mitogens -chemical block -Metaphase STOPS -wash chemical block, cells all go together -chromsomes get smaller & chromosomes become condensed & go from round to OVAL -Prophase: see chromosmes! -prometaphase: shrink down & compacted-need to move & HARVEST (hypotonic soln: h20 inside; cell swells) cell stretches out -suck up soln -drop cells on clean slate & break them, take a pic & blow up -get scissors & cut out &place together -EYES CONFIRMMMMMMMMMMMM
ovulation process? -most mature oocyte in 1 ovary bursts out each month
-oocyte drops into uterine tube, where waiving CILIA move it toward the uterus. *-oocyte -uterine tube -(cilia):uterus
meiosis in the female is known as: meiosis begins with? occurs in?
-oogenesis -a Diploid cell-->oogonium ARE NOT ATTACHED; *follicle cells** surround each oogonium -ovaries
-testes covered by epididymis(tightly coiled tube), which makes up the scrotum -epididymis goes to ductus deferens:bladder:urethra(tube that carries sperm/urine out through the penis)
-ovary release mature oocye(by cilia): fallopian tubes:uterus -(may meet sperm-in uterine tube=fertilized ovum) -cell divides & settles in uterus lining-->continue to divide, an embryo develops -**no fertilization= oocyte+uterine lining shed during menstrual -uterus:cervix:vagina
How does chromosome microarray analysis work?
-paired w. the older techniques to detect copy # variants, which include extremely sm. sections of missing or extra DNA; probes & displays specific sequences, detecting many disorders that other techniques miss
what are the 2 types of inversions?
-paracentric inversion -pericentric inversion
in secretion, the rough ER is the site of----? smooth ER?
-protein synthesis & folding -site of lipid synthesis, transport & packaging
signal transduction (book) pg. 35
-receptor binds a 1st messenger, triggering a cascade of biochemical activity at the cell's surface. -an enzyme catalyzes a rxn inside the cell that circularizes ATP to cyclic AMP, the 2nd messenger. -cAMP then stimulates responses, such as cell division, metabolic changes, & muscle contraction. -spitting ATP also releases energy
meiosis 1 meiosis 2
-reduction division bc it reduces the # of replicated chromsomes from 46 to 23 -equational phase: produces 4 cells from the two cells formed in the first division by splitting the replicated chromosomes
PROPHASE?
-replicated chromosomes consisting of 2 CHROMATIDS condense, the spindle assembles, the nuclear membrane breaks down, and the nucleolus is no longer visible
sperm cells are manufactured in the _____?
-seminiferous tubules, which wind tightly within the testes, which Descend into the scrotum
each sperm consists of?
-tail -body/midpiece -head region
what are the essential parts of a chromosome?
-telomeres -origin of replication sites, where replication forks begin to form -Centromere
ring chromosomes arise when?
-telomeres are broken/lost, leaving sticky ends that adhere (genes can be lost or disrupted) -radiation can form rings -can form from ANY chromosome & may be 1 of the 46 chromosomes or an extra
ANAPHASE 1 TELOPHASE 1 CYTOKINESIS 1
-tetrads break apart & become DYADS & separate to opposite poles -Nuclear envelope partially assemble around DYADS, spindle disappears, finish moving to opposite poles -Divides cell into two
what would happen without meiosis?
-the sperm & oocyte would each contain 46 chromosomes, & the fertilized ovum would have 2X the normal # of chromosomes(92)--->polyploid
before fertilization occurs, what must happen?
-the sperm's acrosome bursts, spilling enzymes that help the sperm's nucleus enter the oocyte -----only ONE sperm can enter an oocyte
why can inversions become so drastic?
-traced to meiosis, when crossing overs occurs b/t in inverted chromosome segment & the noninverted homolog -to allow the genes to align, the inverted chromosome forms a loop, some areas are duplicated and some deleted in the resulting recombinant chromosomes.
what 2 types of lung stem cells are needed?
-type that secretes surfactant, which is the chemical that inflates air sacs -cell type that exchanges oxygen for carbon dioxide
GROUP A consists of?
1 (meta) 2 (sub) 3 (meta) ***only group w. 2 different shapes)
3 types of translocations?
Robertsonian translocation reciprocal translocation non-reciprocal translocation
(PERICENTRIC) normal chromatid + inversion chromatid=?
1. normal chromatid 2. Abnormal: duplication & deletion 3. Inversion chromatid 4. Abnormal: duplicat & deletion ***centromere in middle**
(PARACENTRIC) normal chromatid + inversion chromatid =?
1. normal chromatid 2. Dicentric: duplication & deletion (2 centromeres-BAD!) 3. Inversion chromatid 4. Acentric fragment (no centromere-floats around, cant move) ***centromere(s) at top(/bottom or not at all)
*******movement through a cell of Info? (steps)
1.) Genes that encode milk proteins & certain enzymes are transcribed into mRNA 2.) mRNA exits through nuclear pores 3.)mRNA moves to surface of rough ER, where proteins are synthesized on ribosomes using A.A. in the cytoplasm 4.) lipids are synthesized in the smooth ER 5.)Sugars are synthesized & proteins folded in the Golgi apparatus, then both are released in vesicles that bud off of the Golgi 5.) protein- & sugar-laden vesicles move to the plasma membrane for release. Fat droplets pick up a layer of lipid from the plasma membrane as they exit the cell
signal transduction steps?
1.) receptor binds an INCOMING molecule (1st messenger) 2.) receptor contorts, touching a nearby protein called REGULATOR 3.) regulator activates a nearby enzyme, which catalyzes a specific rxn 4.) the product of this rxn, called the 2ND MESSENGER, is the KEY part of the entire process--elicits the cell's response(usually activation of certain enzymes)
cytoskeleton: 1.) microtubules 2.) intermediate 3.) microfilaments
1.)tubules: spindle fibers, cilia 2.) intermediate: mechanical strength of membranes, keratins --why cells stay the shape they are 3.) mircofilaments: cell to cell anchors, CONTRACTILE -how cells change shape
3 common aneuploids:Autosome trisomy?
13 (patau) 18 (Edward) 21 (down)
group d?
13, 14, 15 ACROCENTRIC ********survivor of extra chromo
which 5 chromosomes have satellites?
13, 14, 15, 21, & 22
group e?
16, 17, 18 (submet)
Group f?
19, 20 (meta)
PRIMARY germ layers form in the____wk? Cells in a specific germ layer later become parts of particular organ system as a result of DIFFERENTIAL gene expression
SECOND WEEK
what happens in meiosis 1 to the 1^ oocyte?
1^ oocyte divides into two cells: - 1ST POLAR BODY -Secondary Oocyte
sm. cell w/ very little cytoplasm
1st polar body
(m2) 2 products of the 1st division are unaffected, 2 of the mature sperm are _______ & two are _____?
2 are normal; 2 are aneuploid
spermatogonium divides mitotically, yielding?
2 daughter cells---1 continues to specialize into a mature sperm; the other-remains a stem cell, able to self-renew & continually produce more sperm
in robertsonian translocation the long arms of the different-------- join?
2 different acrocentric chromosomes join
reciprocal translocation?
2 different(nonhomologs) chromosomes exchange parts; 2 chromosomes swapping that aren't supposed to
fraternal/DIZYGOTIC
2 sperm fertilize 2 oocytes (ovulation occursin2 ovaries in the same month, or if 2 oocytes leave the same ovary & are both fertilized)
fraternal twins result from?
2 sperm fertilizing two 2^ oocytes **own amniotic sacs, yolk sacs, allantois, placentas, & umbilical cords
group G
21, 22 ACRO
primary oocytes have the diploid #of?
23 chromosome PAIRS
gametes contain?
23 different chromosomes, constituting one copy of the genome
approx. ____days after a single sperm burrowed its way into an oocyte, a baby is ready to be born
266 days
following sexual intercourse, sperm are capacitated & drawn to -----?
2^oocyte
how many cells are produced at the end of meiosis 2?
4 HAPLOID CELLS
in the 2nd meiotic division, each of 2 cells from the 1st division divides again, yielding?
4 cells from the original one
group b consists of?
4, 5 (submetacentric)
how many chromosomes does a translocation carrier have?
45, but may not have symptoms if no crucial genes have been deleted or damaged. -may Produce unbalanced gametes-sperm/oocytes w. too many or too few genes--->spontaneous abortion or birth defects
what is unique about groups D & G???
5 pairs =ACROCENTRIC P-arms contain material to (nucleus) genes to make RNA for making ribosomes---ribosomal RNA
group c consists of?
6-12 (Submeta)
molecules on the plasma membrane assess, transmit, & amplify incoming messages to the cell's interior.
SIGNAL TRANSDUCTION
the formation/generation/production of sperm cells?
SPERMATOGENSIS
in signal transduction the cell changes various types of ___?
STIMULI into specific biochemical rxns
In response to specific hormonal cues each month, 1 ovary releases..
A SECONDARY OOCYTE--"Ovulation"
NECROSIS?
A form of cell death associated w. INFLAMMATION, rather than an orderly, contained destruction
which group (metacentric, sub, acro,etc.) can survive w. an EXTRA chromosome?
ACROCENTRIC
______assist the sperm's penetration of the oocyte. Chemical & electrical changes in the oocyte's surface block additional sperm.
ACROSOMES
_____rapidly & neatly dismantles a cell into membrane-enclosed pieces that a phagocyte can mop up?
APOPTOSIS
the bell of cells hollows out, & its center fills w/ fluid, creating?
BLASTOCYST
yolk sac & allantois manufacture?
BLOOD CELLS, the umbilical cord forms, & the amniotic sac expands w. fluid
1st polar body & secondary oocyte have what in common?
Both HAPLOID, w/ chromosomes in replicated form
anaphase????
CENTROMERES part, equally dividing the now unreplicated chromosomes into 2 daughter cells
what are the 2 long strands of identical chromosomal material in a replicated chromosome called?
CHROMATIDS
what 2 types of protein _____ interact inside cells to activate the genes whose products carry out mitosis?
CYCLINS & KINASES -form pairs that may turn on genes that trigger mitosis. then as mitosis begins, enzymes degrade the cyclin. the cycle starts as cyclin begins to build up during the next interphase
an oogonium accumulates _______ & replicates its DNA, becoming a 1^ oocyte
CYTOPLASM
bridges of _____attach several spermatogonia, & their daughter cells enter meiosis together
CYTOPLASM -as these spermatogonia mature, they accumulate cytoplasm & replicate their DNA, becoming PRIMARY SPERMATOCYTES
nondisjunction in meiosis 2?
Can survive (1x chromosome; 3x chromo) -half Fine -1/4 mono -1/4 tri
what are the locations on a chromosome (in order):
Chromosome #: (1-22) X or Y Arm: p or q Region Band Subband
gradually, the DNA includes more protein-encoding sequences w/ ______ from the centromere?
DISTANCE; gene density varies greatly among chromosomes
within the large sperm head, _____ is wrapped around proteins?
DNA -Sperm's DNA at this time is genetically INactived
the nucleus contains?
DNA & nucleolus
What happens during PROPHASE?
DNA coils tightly.-->shortens & thickens the chromosomes, which enables them to more easily separate. -MICROTUBULES assemble from tubulin building blocks in the cytoplasm to form spindles -toward the end of prophase, the nuclear membrane breaks down. the NUCLEOLUS IS NO LONGER VISIBLE.
ring chromosomes mostly consist of?
DNA repeats & are not harmful, EXCEPT CHROMO 20
During a 2nd interphase...?
DYADS(chromosomes) unfold into very thin threads -proteins are manufactured, but DNA is NOT replicated a 2nd time "resting phase" -makes protein; use/decompose DNA (the single DNA replication, followed by the double division of meiosis, HALVES the chromosome #)
stem cells
Diploid cells that both give rise to differentiated cells and replicate themselves in a process called self-renewal
haploid sperm & oocyte are derived from?
Diploid germline cells by meiosis & maturation
2nd wk of Prenatal development-a space called the AMNIOTIC CAVITY forms b/t the inner cell mass & the outer cells anchored to the uterine lining. then the inner cell mass flattens into a 2-layered embryonic disc
ECTODERM: layer nearest the amniotic cavity ENDODERM: inner layer, closer to the blastocyst cavity MESODERM: forms in the middle
oocytes arrest at PROPHASE1 until puberty, after which 1 or several oocytes complete the 1st meiotic division each month. the 2nd meiotic division completes at...?
Fertilization
3-layered(primary germ layers) structure is called?
GASTRULA, or the primordial embryo
what makes up the 3 layers of the embryo?
GASTRULA-ecto, meso, endo
a loaded vesicle takes its content to the next stop in the secretory producing line----?
Golgi apparatus. this processing center is a stack of flat,membrane-enclosed sacs ---proteins finish folding in the golgi
In meiosis 1, each primary spermatocyte ______its genetic material to form TWO 2ndary spermatocytes
HALVES its genetic info.
Separation movements of DYADS establishes?
HAPLOID set of still-replicated chromosomes at each end of the stretched-out cell
what are genes that control how the embryo develops parts in the right spaces?
HOMEOTICS /HOMEOTIC GENES
progenitor cell cannot?
Self-renew, & its daughters specialize as any of a restricted # of cells
the prostrate gland, seminal vesicles, and bulbourethral glands add secretions to the sperm cells to form?
Seminal fluid
WHAT are the "master genes"?
Homeotic genes
MONADS ARE...?
IN GONADS
"reprogramming" somatic cells to differentiate into any of several cell types?
Induce pluripotent stem (iPS) cells ---cell make have to go back in time to developmental time to an ES cell-like state & then the cell divides & gives rise to cells that specialize as a different, desired cell type ORRRR ---cells can be reprogrammed directly into another cell type (biology major wants to become chem major--don't need to start from scratch bc of similar courses) ***iPS cells do not require the use of ANY cells from an embryo****
47, XYY
Jacobs syndrome-males "criminals"
47, XXY
Klinefelter syndrome-MALES
molecule that binds to the receptor?
LIGAND, may set into a motion a cascade of chemical rxns inside the cell that carries outa particular activity
chromosome 4 houses ______genes, and genome-wide screen are identifying other.
LONGEVITY
smooth ER
Lipids are made and added to the proteins arrivingfrom the rough ER
after puberty, meiosis 1 continues in 1 or several oocytes each month, but HALTS again where?
METAPHASE 2
Diploid cells divide through ____in the linings of the SEMINFEROUS TUBULES? Some of the daughter cells then undergo Meiosis, producing ________, which differentiate into mature sperm cells.
MITOSIS haploid spermatocytes
SPINDLE ASSEMBLY CHECKPOINT?
MITOSIS; oversees construction of the spindle and the binding of chromosomes to it
Cleavage cell division form a ____& then a _______?
MORULA; BLASTOCYst
2.) in response (to the biochemical message) info. in certain genes is copied into molecules of-----------?
Messenger RNA, which then exit the nucleus.
when the blastomeres form a solid mass/ball of 16 or more cells, the embryo is called?
Morula
paracentric inversion?
NO CENTROMERE, single crossover w/in the inverted segment gives rise to 2 normal & 2 atypical chromosomes
can a mature blood cell be used to examine chromosomes?
NO, NO NUCLEUS
what is the name of meiotic error that causes aneuploidy?
NONDISJUNCTION
The woman's body absorbs the polar bodies, which?
NORMALLY plays no further role in development **rarely a sperm fertilizes a polar body-->woman's body responds as if she is pregnant, but a disorganized clump of cells that NOT an embryo grows for a few weeks, & then leaves the woman's body. "blighted ovum" miscarriage
lack of B vitamin folic acid causes?
NTD
little nucleus?
NUCLEOLUS; Inside the nucleus-area that appears darkened -RIBOSOMES ARE PRODUCED!!
eukaryotes
NUCLES -Organelles
Most prominent organelle of the cell?
NUCLEUS-enclosed inside a layer called the nuclear envelope -biochemicals can enter/exit the nucleus through nuclear pores, which are rings of proteins like portholes in a ship's side
How can a cell "know" how many divisions remain?
TELOMERES:chromosome tips -function like cellular fuses that burn down as pieces are lost from the ends. -consist of 100's-1000's of repeats of specific 6 DNA-based sequences. -Each mitosis= telomeres shortening (50 divisions, critical length of telomere DNA is lost, which signals mitosis to STOP. the cell may remain alive but never divide again, or die)
Most of the cytoplasm among the 4 meiotic products in the female ends up only where?
THE OVUM CELL
the outermost cells of the blastocyst?
Trophoblast
45,X?
Turner syndrome-Female
fertilized ovum----------------------?TOTIPOTEN
ULTIMATE STEM CELL;;;; -totipotent: it can give rise to every cell type, including the cells of the membranes that support the embryo
inheriting 2 chromosomes or chromosome segments from 1 parent
UNIPARENTAL DISOMY (UPD)
2ndary oocyte divides_______in meiosis 2 to produce another SM. POLAR BODY, w/ UNreplicated chromosomes, & the mature egg cell, or ovum, which contains a lg. volume of cytoplasm
UNequally
sex chromosomes?
X=C (sub) Y=G (acro)
2 sets of chromosomes meet, forming?
a ZYGOTE
mitosis (dividing)
a cell duplicates it chromosomes, then in cytokinesis it apportions one set into each of two resulting cells, called daughter cells--this division maintains the set of 23 chromosome pairs characteristic of a somatic human cell.
how does signal transduction amplify incoming info?
a single stimuls can trigger the production of many 2ND MESSENGER MOLECULES -since cascades of protein carry out signal transduction, it is a GENETICALLY controlled process
In meiosis 1, the 1^ oocyte divides, forming?
a sm.polar body & a lg Haploid 2ndary oocyte
in signal transduction?
a stimulus (1st messenger) activates a cascade of action among membrane proteins, culminating in the production of a 2nd messenger that turns on enzymes that provide the response.
robertsonian translocation produces?
a. balanced (normal karyotype) b. balanced (translocation carrier) C. Excess 21 (translocation Down syndrome) d. Excess 14 (spontaneous abortion) e. Deficient 21 (spontaneous abortion) f.) deficient 14 (spontaneous abortion)
identical twins originate at 3 points in development:
a.) separate amnions & chorions (1/3) b.) share amnion & chorion (less than 1%) c.) share chorion but have separate amnions
what makes a stem cell?
ability to continue the lineage of cells that can divide to give rise to another cell like its self
when does meiosis finish?
after FERTILIZATION
G2 occurs?
after the DNA has been replicated BUT BEFORE mitosis begins
Bulbourethral glands:
alkaline mucus that coats the urethra before sperm is released
3rd week of prenatal development, PRIMITIVE STREAK BAND appears?
along the back of the embyro
How can chromosomes of a fetus be checked?
amniocentesis (1&2 detect lg-scale chromosome abnorm) chorionic villus sampling chromosome microarray analysis
when the replicated (sister) chromatids separate at ____, each member of the pair retains some CENP-A. (the protein therefore passes to the next cell generation, but it is NOT DNA)---EX. of epigenetic change
anaphase
nondisjunction during meiosis causes?
aneuploidy: extra/missing chromosomes
in meiosis 2, the 2^ oocyte divides, yielding?
another small polar body & a mature haploid ovum
caseins?
antibodies that protect against infection and enzymes
cytokinesis
apportions other components into daughter cells
cytogenetics?
area of genetics that links chromosome variations to specific traits
how is the sex determined?
at conception, when a sperm bearing an X or Y chromosome meets an oocyte(always carries X) ***SRY GENE on the Y chromosome determines maleness**
once the primary germ layers form, cells become?
become "determined" or fated, to develop to a specific cell type
as each oogonium grows, cytoplasm accumulates, DNA replicates, and the cell...?
becomes a 1^ OOCYTE
plasma membrane
bilayer of phospholipids molecues; tails: hydrophobic head: hydrophilic
the resulting early cells (after cleavage) is?
blastomeres
peroxisome
breaks down and detoxifies various molecules
(wk 3) the primitive streak appears, followed rapidly by the notochord, neural tube, heart, central nervous system, limbs, digits, facial features, & other organ rudiments
by wk 8, all of the organs that will be present in the newborn have begun to develop
interphase
cell can enter g1 to g0 G0-where a cell maintains its specialized characteristics but does not replicate its DNA or divide -from G0 a cell may also proceed to mitosis and divide, or die. -apoptosis may ensue if the cell's DNA is so damaged that cancer might result
umbilical cord
cells are VALUABLE; ABUNDANT; EASY OBTAIN & MANIPULATE -can be cultured to differentiate as cells from any of the 3 primary germ layers -often used to treat resp. disease of newborns.
chorionic villus sampling (10TH-12th wk)
cells of the chorion are sampled -karyotype prepared DIRECTLY from collected cells-results are ready in days -chromosome ABERRATION MAY occur->chromosomal mosaicism: karyotype of a villus cell differs from that of an embryo cell **great clinical consequences** (less accurate than amniocentesis) -can halt development of feet, hands, or may be lethal -CANNOT test for inborn errors of metabolism
metacentric?
centromere divides into 2 arms of ~ EQUAL length (centromere in middle)
submetacentric?
centromere has 1 long& 1 short arm (centromere creates a long arm & a short arm) **normal***
what causes birth defects? (teratogens)
chemicals: ALCOHOL CIGARETTES VITAMIN A, C STARVATION--intrauterine Growth retardation (IUGR) EPIGENETICS METALS CARCINOGENS VIRUSES (rubella, HIV, herpes complex, hep B) NUTRITION
structures form support & protect the embryo?
chorionic cilli placenta yolk sac allantois umbilical cord amniotic sac
what does mitotic nondisjunction produce?
chromosomal mosaics
meiosis maintains?
chromosome # over generations & mixes gene combinations
what are subtelomeres?
chromosome parts that lie BETWEEN protein-rich areas & the telomeres --include some protein-encoding genes & bridge the gene-rich regions & telomere repeats
isochromosome ?
chromosome w/ IDENTICAL ARMS
METAPHASE?
chromosomes attach to the spindle at their centromeres and align along the center of the cell, which is called the Equator **chromosomes are under great tension**
what are satellites?
chromosomes that have bloblike ends that extend from a thinner, stalklike bridge from the rest of the chromosome **the stalks carry many copies of genes encoding ribosomal RNA & ribosomal proteins. these areas coalesce to form the Nucleolus--where ribosomal building blocks are produced & assembled
after fertilization, the zygote divides by Mitosis, beginning a pd of frequent cell division called?
cleavage
the primitive streak gives rise to?
connective tissue progenitor cells & the notochord
intermediate filaments
consist of paired proteins entwined into nested coiled rods. scarce in many cell types but are very abundant in nerve cells and skin cells
what is a kinetochore?
contacts the spindle fibers, enabling the cell to divide (synthesized only when mitosis is imminent, about to happen)
what do master genes do?
controlling genes that can turn on hundreds of genes @ once ********more complex=MORE homeotic genes
UPD can cause a disease if it?
creates a homozygous recessive condition, of if it disrupts imprinting
crossing over & independent assortment generate further genotypic diversity by?
creating new combos of alleles
stem cells produce?
daughter cells that retain the ability to divide and daughter cells that specialize. *********** progenitor cells give rise to more specialized daughter cells but do NOT self-renew
what does the centromere do?
defines shape of the chromosome
(ovulation) 2ndary oocyte NOT fertilized=??
degenerates & leaves the body in menstrual flow, meiosis NEVER completed
lysosome
degrades debris; recycles cell contents
the repetitive sequence of a telomere gradually diversifies toward______?
differs toward the CENTROMERE
ENDODERM become?
digestive, trachea, parts of the liver & pancreas & the linings of many organs (internal)
3.) in the cytoplasm, the mRNAs, with the help of ribosomes & another type of RNA called tRNA---?
direct the manufacture of milk proteins. these include nutritive proteins called CASEINS, antibodies that protect against infection, and enzymes.
karyotype
displays chromosomes in pairs by size(largest:smallest-1 to 22; X &Y) & by physical landmarks that appear during mitotic metaphase, when DNA coils tightly
during meiosis 1, each primary spermatocyte?
divides, forming 2 equal-sized HAPLOID cells called 2ndary spermatocytes
amniocentesis (15-16 wks)
draws out amniotic fluid; fetal cells shed into the fluid & are collected & their chromosomes examined -cells cultured for a week-10days -also detect for deficient, excess, or abnormal biochemical that could indicate an inborn error of metabolism -specific gene disorders are based on family hx & may be done on cells in the amniotic fluid sample as well -TRISOMY -procedure may cause miscarriage
isochromosome has 2 identical arms, introducing?
duplications & deletions
nondisjunction in meiosis 1?
during 1st division-BOTH chromosomes go to ONE cell instead of splitting -BAD; nothing good. too much info in 1 cell -produces monosomic, monosomic, trisomic, trisomic
How does isochromosomes happen?
during division, the centromeres part in the wrong plane (divide horizontally instead of vertically) -->leads to unbalanced genetic info. -chromos 12 & 21 & for long arms of the X & Y
the inner cell mass develops into the______?
embryo
how to "simese twins" or conjoined twins happen?
embryo divides into twins after the point at which the 2 groups of cells can develop as individuals, b/t days 13 & 15
chorion?
embryonic OUTER tissue; body tissue meets mom's system & exchange air, vitamins, etc. **CAN BE USED FOR: carrier typing & testing**
what does the ER do?
enables the forming protein to start folding into 3-D shape necessary for its specific function. ---- misfolded proteins are pulled out of the ER and degraded
4.) most protein synthesis occurs on a maze of interconnected membranous tubules and sacs---?
endoplasmic reticulum
central nervous system-brain- 's critical period?
entire 9months
sirtuins?
enzymes that regulate energy use in cells by altering the expression of certain sets of genes ***seem to prevent or delay several disease that are more common in the aged
sperm mature & are stored in the ______ & exit through the ductus deferens
epididymis
where is mature sperm stored?
epididymis
What controls genes through lifestyle?
epigenetics
pseudo genes?
false, something is missing. NOT EXPRESSABLE
independent assortment:
fate of a gene on 1 chromosome is NOT influenced by a gene on a different chromosome---BASIC LAW OF INHERITANCE
what does the amniotic fluid contain?
fetal urine & cells
chrionic villi
fingerlike outgrowths that extend from the area of the embryonic disc close to the uterine wall -villi project into woman's blood; blood system & embryo's is SEPARATE, but nutrients & o2 diffuse across the chorionic villi from her circulation to the embryo.
nucleoplasm
fluid in the nucleus
what happens in a non-reciprocal translocation
gaining->duplication losing->Deletion
epigenetics
gene regulators; can change gene structure or turn gene on/off
the cells of all 3 domains contain?
globular assemblies of RNA and protein called RIBOSOMES that are essential for protein synthesis.
cellular adhesion molecules (CAMs)?
guide WBC in injury sites using a sequence of cell-protein interactions
where does meiosis begin for a guy & girl
guy: seminiferous tubules girl: ovaries (pair)
certain blastocyst cells secrete?
hCG
in the 1st meiotic, the # of chromosomes is?
halved
lysosomes (intracellular digestion)
handle the garbage/debris that builds up in cells --membrane-bounded sacs that contain enzymes that dismantle bacterial remnants, worn-out organelles, and other material such as excess cholesterol -break down some digested nutrients into forms that the cell can use
what does a Euploid somatic human cell?
has 22 pairs of AUTOSOMES & 1 pair of sex chromosomes
telocentric?
have only ONE arm----humans do NOT have
if the chromosome exchange does not break any genes, then a person who has both translocated chromosomes is?
healthy & a translocation carrier -normal amount of genetic material, just rearranged
tail/flagella?
help the sperm swim the long way from the vagina to the fallopian tube where it fertilizes the egg
centromeres lie within vast stretches of ______?
heterochromatin
what is Blastula?
hollow ball that implants in uterine wall
meiosis 1=? meiosis 2=?
homologous chromosomes sister chromatids
Spermatogensis begins?
in a diploid stem cell called spermatogonium
primary oocytes stop?
in prophase 1
sperm develop in the seminiferous tubules, mature & collect in each epididymis, enter the ductus deferentia, & move through the urethra in the penis. the prostrate gland adds an alkaline fluid, seminal vesicles add fructose and prostaglandins, & bulbourethral glands secrete mucus to from seminal fluid.
in the female, ovaries contain oocytes. each month, an ovary releases an oocyte, which enters a uterine tube leading to the uterus. if the oocyte is fertilized, It begins rapid cell division & nestles into the uterine lining to divide & develop. otherwise, the oocyte exits the body. hormones control the cycle of oocyte development
pericentric inversion
includes centromere w/in the loop -crossover in it produces 2 chromosomes that have duplications & deletions, but one centromere each
Some of the cells form a clump on the inside lining called?
inner cell mass ***its formation is the 1st event that distinguishes cells from each other by their relative positions, other than inside & outside the morula; the inner cell mass continues developing, forming the embryo
meiosis occurs after?
interphase pd when DNA is replicated -for each chromosome pair in the cell undergoing meiosis, 1 homolog comes from the person's mother/other-dad
Head has an acrosome that..?
is filled w/ stuff (enzymes) that can break down the fluid surrounding the egg & the head contains genetic info. needed to create a baby
gene duplications & deletions can occur in ----------?
isochromosomes and ring chromosomes and when inverted chromatids cross over
what is a DNA probe?
labeled piece of DNA that binds to its complementary base sequence on a particular chromosome
prokaryotes
lack a nucleus (structure that contains DNA in the cells of other types of organisms)
centromere
largest constriction of a chromosome; where spindle fibers attach when the cell divides -made up mostly of DNA & protein
corona radiata
line of cells
DNA repair enables us to do what?
live many years
microfilaments
long, thin rods composed of many molecules of the protein actin. enables cells to withstand stretching and compression, and help anchor one cell to another
_____contains enzymes that dismantle debris
lysosomes
autophagy; self eating
lysosomes fuse w/ vesicles carrying debris from outside or within the cell, and the lysosomal enzymes then degrade the contents
what does a chromosome consist of?
mainly DNA & proteins w/ a sm. amount of RNA
yolk sac
manufactures blood cells;; toward the end of the embryonic pd, the yolk sac shrinks, & the amniotic sac swells w/ fluid that cushions the embryo & maintains a constant temp & pressure
The base of the tail (flagellum) has??
many mitochondria, which will split ATP molecules to release energy that will propel the sperm inside the female reproductive tract.
MESODERM becomes?
many structures-muscle, connective tissues, the reproductive organs, & the kidneys
what can reveal (+ed) risk of an atypical chromosome #?
maternal serum marker patterns & ultrasound scans
in meiosis 2, the tiny 1st polar body..?
may divide to yield 2 polar bodies of equal size, w/ UNreplicated chromosomes; OR the 1st polar body may decompose
mitosis: 1.) 1 division 2.) 2 daughter cells/cycle 3.) Daughter cells genetically identical 4.) Chromosomes # of daughter cells same as that of parent cell (2N) 5.) occurs in Somatic cells 6.) occurs throughout life cycle 7.) used for growth, repair, & asexual reproduction
meiosis: 1.) 2 divisions 2.) 4 daughter cells/cycle 3.) Daughter cells genetically different 4.) chromosomes # of daughter cells half that of parent (1n) 5.) occurs in germline cells 6.) in humans, completes after sexual maturity 7.) used for sexual reproduction, producing new gene combinations
route of male? -------------------notes* testes:seminiferous tubules gonads:scrotum epididymis ductus deferens seminal vesicles prostrate gland bulbourethral glands semial fluid urethra
meiosis=GONADS->epididymis->ductus deferens->seminal vesicle->Prostrate gland->bulbourethral gland->urethra
VESICLES
membrane-bounded, sac like organelle ---- where proteins exit the ER
cytoskeleton
meshwork of protein rods and tubules that molds the distinctive structures of a cell a.) microtubules b.) microfilaments c.) intermediate filaments
what happens in the Golgi apparatus?
milk sugar lactose is synthesized and other sugars are made that attach to proteins to form glycoproteins or to lipids to from glycolipids, which become parts of plasma membranes
what does the syndrome progeria do?
mimics aging
enzymes in ______extract energy from nutrients
mitochondria
trisomies are less severe than _____? sex chromosomes aneuploidy is less severe than -----?
monosomies -autosomal aneuploidy
when a sperm cell w. 2 copies of the chromosome fertilizes a normal oocyte, the zygote is trisomic; when a sperm cell lacking the chromosome fertilizes a normal oocyte, the zygote is?
monosonic
euchromatin has?
more protein-encoding sequences
heterochromatin(DARK) contains mostly of what?
mostly of highly repetitive DNA sequences
secondary oocyte?
much larger cell (than 1st polar body)
telophase?
new cells separate
nuclear lamina?
on the inner face of the nuclear membrane is a layer of fibrous material --dna in the nucleus touches the nuclear laminas it divides --also provides mechanical support and holds in place the nuclear pores ------------abnormal aging=from nuclear lamina
Meiosis in females is UNEVEN, concentrating most of the CYTOPLASM into?
one large cell called an oocyte/egg
oogenesis process
oogonium(diploid) MITOSIS; 1^ Oocyte (diploid) MEIOSIS 1; a.)1st polar body may divide (haploid) b.) 2^ oocyte (haploid) MEOISIS 2 ***IF fertilization occurs** a.) polar bodies die b.) Ovum (egg) c.) Second Polar body (haploid) !!!!ONE MATURE EGG!!!!!
placenta
organ that links woman and fetus for the rest of pregnancy -secretes hormones that maintain pregnancy & alter the woman's metabolism to send nutrients to the fetus
route of female reproductive system
ovaries:ova already made-p1 uterine/fallopian tube uterus/womb *menstrual flow removes unused/problem eggs through Vagina
cleavage: from ovulation to Implantation ****Rapid Mitosis
ovary(ovulated 2^ oocyte) fertilization-->ZYGOTE uterine tube morula inner cell mass blastocyst implants EMBRYO
______house enzymes that perform a variety of functions
peroxisomes
acrocentric?
pinches of only a small amount of material toward one end (centromere near an end)
chorion develops in the?
placenta
have extra sets of chromosomes & do not survive for long
polyploids
meiosis
produces sperm or egg, which have HALF the amount of genetic material in somatic cells or 23 SINGLE chromosomes.
oogenesis?
production of eggs
progerin shifts the activities of certain genes in ways that?
promote bone formation & suppress fat deposition
oocytes develop w/in the ovary in?
protective follices
zona pellucida
protective wall
What do telomeres do?
protects ends from shortening
cytoskeleton?
protein framework of hollow microtubules, made of tubulin, & solid microfilaments, which consist of actin. -intermediate filaments are made up of more than 1 protein type and are abundant in skin. -cytoskeleton & the plasma membrane distinguish different types of cells
what is CENP-A?
protein that may control the process of replication
during g2 more ____ are synthesized?
proteins --membranes are assembled from molecules made during g1 & are stored as small, empty vesicles beneath the plasma membrane. these vesicles will merge with the plasma membrane to enclose to 2 daughter cells
ribosomes do what?
provide scaffolds for protein synthesis; they exit free in the cytoplasm or complexed w. the rough ER
microtubules
provides many cellular movements; composed of pairs of protein, called tubulin, assembled into a hollow tube. the cell can change the length of the tubule by adding or removing tubulin molecules -form CILIA-coordinated movements generates a wave that moves the cell or propels substances along its surface
robertsonian translocations:
q + q (p arms lost) -taking 2 chromosomes & making (1) new one. -Acrocentric: ribosomal RNA genes
which is LARGER the p or q arm?
q arm= LARGER
process of apoptosis?
receptor on the plasma membrane receives a death signal, which activates CASPASES that tear apart the cell in an orderly fashion. membrane surrounds the pieces, preventing inflammation.
most single-gene disorders are ______?
recessive & strike early in life. -single-gene disorders w. an adult onset are more likely to be dominate
what kind of translocation do chromosomes exchange parts?
reciprocal translocation
mitochondrion
releases energy from nutrients, participates in cell death
METAPHASE???
replicated chromosomes align along the center of the cell
when mitosis begins?
replicated chromosomes condense
S phase
replicates DNA
R band?
reverse of G band
characteristcs of a dying cell?
rounds up as contact w. other cells are cut off, & the plasma membrane undulates, forming bulges called BLEBS. -nucleus bursts, releasing the same-sized DNA pieces. -mitochondria decompose; cell shatters. & almost instantly, pieces of the membrane encapsulate the cell fragments which prevents inflammation. w/in an hr, cell is gone.
peroxisomes
sacs w/ outer membranes that are studded with several types of enzymes that perform a variety of functions, including the breakdown of certain lipids and rare biochemicals, synthesizing bile acids used in fat digestion, and detoxifying compounds that result from exposure to oxygen free radicals
aminocentesis
sample of amniotic fluid is taken & fetal cells in it are examined for biochemical, genetic,& chromosomal abnormalities
ribosome
scaffold and catalyst for protein synthesis
most severe rapid aging disorders are?
segmental progeroid syndromes -impairment of the cells' ability to repair DNA; overm time, the accumulation of mutations occur in somatic cells.
seminal vesicles + prostrate gland + bulbourethral gland=?
seminal fluid (all combine)--->CARRIES SPERM
sperm cells develop within a network of?
seminiferous tubules, which are packed into paired TESTES(male gonads)
nucleus
separates DNA within cell
TELOPHASE?
set of Chromosomes at each end -spindle falls APART, & nucleoli & the membranes around the nuclei REFORM @ each elongated cell. -DIVISION OF GENETIC MATERIAL IS COMPLETE!!!
2 types of interactions among cells?
signal transduction & cellular adhesion
identical/MONOZYGOTIC
single fertilized ovum & therefore are genetically identical -natural clones
the segmental progeroid syndromes are-----disorders that speed the sings of aging
single-gene
endoplasmic reticulum
site of protein synthesis and folding; lipid synthesis
what is the nucleolus?
site where ribosome synthesis occurs
Golgi apparatus
site where sugars are made and linked into starches or joined to lipids or proteins; proteins finish folding; secretions stored
cells in the ECTODERM become?
skin, nervous tissue, or parts of certain glands *nervous system*
why does meiosis half the amt of genetic material?
so that the full amt is restored when sperm meets egg
after spermatid differentiation?
some of the cytoplasm connecting the cells falls away, leaving mature, tadpole-shaped SPERMATOZOA or sperm
embryonic induction
specialization of 1 group of cells causes adjacent groups of cells to specialize-->gradually these changes make up the 3 germ layers into organs & organ systems
Spermatogonium (diploid stem cell) MITOSIS; primary spermatocyte(diploid) MEIOSIS 1; 2ndary spermatocyte (Haploid) MEIOSIS 2; Spermatid (haploid) MATURATION; Sperm (haploid)
sperm formation: Spermatogenesis *MEIOSIS 2->Spermatid:useful ******sperm=mature spermatid; DNA has to be jammed into sperm head & able to swim
Each spermatid develops the characteristic of??
sperm tail, FLAGELLUM
oogenesis: 1 egg= 1 ovum, 3 polar bodies
spermatogenesis: 1 egg= 4 sperm
what is the energy solution to propel self(sperm)?
spiral MITOCHONDRIA
G BAND?
stained dark w. Giemsa
during cleavage, some of the embryo's genes?
start to function
stem/progenitor (book)
stem cell is LESS specialized than the progenitor cell that descends from mitosis. various types of stem cells provide the raw material for producing the specialized cells that comprise tissues, while retaining the ability to generate new cells. a hematopoietic stem cell resides in the bone marrow & can produce progenitors whose daughter cells may specialize as certain blood cell types.
secretion of human chorionic gonadotropin does what?
stops menstrual flow
what is a notochord?
structure that forms the basic framework of a skeleton
receptors
structures that have indentations or other shapes that fit and hold molecules outside the cell
if a translocation leads to a deletion or duplication or disrupts a gene, then?
symptoms may occur
inversions occur bc?
synapsis still must occur & chromosomes are FLEXIBLE so they form inversion loops
all cells??
synthesize proteins for basic "house keeping" functions, such as energy acquisition & protein synthesis
enzyme that keeps chromosome tips long?
telomerase
ring chromosomes form when?
telomeres are missing
what does a DNA damage checkpoint do?
temporarily pauses the cell cycle while special proteins repaor damaged DNA
vesicle
temporarily stores or transports substances
what happens in meiosis 1?
the CENTROMERES of each homolog in meiosis 1 remain TOGETHER
chromosomes number is halved bc ?
the DNA replicates once, but the cell divides twice
a mature sperm has a TAIL, BODY, AND HEAD, with??
the HEAD has an enzyme-containing ACROSOME covering the head
nutrients & oxygen enter the embryo, and wastes pass from the embryo into?
the MATERNAL circulation
homologous pairs or homologs have ----?
the SAME genes in the same order but may carry different alleles, or variants, of the same gene
1.) Secretions begin when? (eukaryotic)
the body sends a biochemical message to a cell to begin producing a particular substance.
interphase is divided into G1 & G2 (& S) when?
the cell duplicates specific molecules and structures --G1;G0--G0:"time-out" when a cell "decides" which course of action to follow
during g1
the cell resumes synthesis of proteins, lipids, & carbs. these molecules will contribute to building the extra plasma membrane required to surround the 2 new cells that form from the original one. ----cells of embryo may skip; some cells may be there forever
in inversions, the atypical chromosomes result from?
the chromatids that crossed over
2/3 of all birth defects arise from a disruption during?
the embryonic pd
what would happen to an oocyte if the division would be equal?
the oocyte would accumulate abundant cytoplasm that would have gone into meiotic product that became the POLAR BODY
mRNA attaches to??
the ribosomes on the ROUGH ER....amino acids from the cytosplasm are then linked, following the instructions in the mRNA's sequence, to form particular proteins that will either exit the cell or become part of membranes
what happens in a robertsonian translocation?
the short arms of two different Acrocentric chromosomes break, leaving sticky ends on the 2 long arms that join, forming a single, lg. chromosome w. 2 long arms
during s phase?
the whole genome is replicated---each chromosome then consists of 2 copies joined at an area called the CENTROMERE. (8-10hrs)
(ovulation) what happens IF sperm penetrates the oocyte membrane?
then female meiosis COMPLETES, & a fertilized Ovum forms
Prostrate gland
think, milky alkaline fluid that activates sperm to swim (needs to be turned on)
what is a critical pd?
time when genetic abnormalities, toxic substances, or viruses can alter a specific structure
FISH gives ability to?
to highlight individual genes; VERY PRECISE & TARGETED -each dot represents a specific DNA sequence to which the fluorescently-labeled probe complementary base pairs
in meiosis 2, each 2ndary spermatocyte divides?
to yield 2 equal-sized SPERMATIDS
when do centromeres replicate?
toward the end of s phase
organogeneis
transformation of the simple 3 layers of the embryo into distinct organs ***during the weeks of organogenesis, the developing fetus is particularly sensitive to environmental influences such as chemicals & viruses
the paired ductus deferentia join in the urethra, which?
transports seminal fluid from the body
iPS ISNT USED FOR?
treating a disease;;;;;RESEARCH!
which is the most common autosomal aneuploid?
trisomy 21, then 18 & 13
APOPTOSIS CHECKPOINT?
turns on as MITOSIS BEGINS. -proteins called SURVIVINS over-ride signals telling the cell to die, ensuring that mitosis rather than apoptosis occurs.
reciprocal translocation do not occur at random among the chromosomes, but involve specific chromosomes that have-------?
unstable parts -vulnerable parts of chromosomes arise where the DNA is so symmetrical in sequence that complementary base pairing occurs within the same DNA strand, folding it into loops & crosses during DNA replication. *these contortions can cause double-strand breaks, which enable parts of2 different chromosomes to switch
FISH (chromosome staining)
uses DNA probes that are complementary to specific DNA sequences. the probes are attached to molecules that fluorescent when illuminated, producing a flash of color precisely where the probe binds to a chromosome in a patient's sampling.
The outer layer of cells invade& implants in the?
uterine lining
a week after conception, the blastocyst nestles into?
uterine lining----->Implantation(1 wk)
where does fertilization take place?
uterine/fallopian tube
the plasma membrane is a protein-studded phospholipid bilayer that controls?
which substances enter or exit the cell
totipotent pluripotent multipotent
zygote stem cells progenitor cells---more restrictive
Prenatal development:
zygote,CLEAVAGE->producing blastomeres Morula (solid ball of Blastomeres)