W2 Flashcards
- What are the 4 stages of mitosis, describe each.
2. conversion of 2n content of DNA into?
- Prophase (DNA has been replicated and the duplicated chromosomes are arranged as sister chromatids, attached at the centromere)
- Metaphase (the sister chromatids line up in preparation for cell division)
- Anaphase (sister chromatids separate)
- Telophase (cell division)
2n content of DNA –>4n preparation for cell division–>2 daughter cells (2n)
Meiosis generate what type of cells?
How many divisions?
Describe the chromosome/sister chromatids in the process.
- generate haploid cells from diploid cells –
- two cell divisions are required.
- After the first division, the sister chromatids are still attached, as opposed to separated as in mitosis.
- The second cell division then separates the identical chromosomes.
Describe Independent Assortment of Chromosomes
As chromosomes migrate to daughter cells during meiotic division, they do so independently of other chromosomes (otherwise, Mendelian genetics would not work)
independent assortment of nonhomologous chromosome during meiotic division I
Crossing over in meiosis happens when? What type of chromosome is involved? The ares of crossing over is called? How many cross overs during division and per chromosome? What does this link to?
- prophase I of meiosis (synapsis)
- pairs of sister chromatids crossover of genetic material can occur btw chromatids
- chiasma
- 30-40 (1-2)
- genetic linkage
Definition of:
- Metacentric
- submetacentric
- acrocentric
- telomere
- chromosome arms
- centromere center
- centromere non-centere
- stalk
- end of chromosome
p=short; q= long
banding patterns of chromosomes
- two types of treatments, describe
- What allows further subdivision into what?
- Other banding techniques? (5)
- enzymatic tx with trypsin & stain chromosomes
- G-banding (Giemsa)–>light band=euchromatin, transcriptionally active; dark abnd= heterochromatin - Giemsa binds better to AT rich region–>subdivsion of regions & sub-region (14q21)
- Q-banding (fluorescent)
R-banding (reverse banding from Giemsa, need to heat DNA)
C-banding (highlights centromeres; remove proteins)
Spectral karyotypes (either chromosome specific, or analyze different areas of the same chromosome)
FISH – fluorescent in situ hybridization
Chromosome & karyotype nomenclature Meaning of & example relating to chromosome 1. 1-22 2. X, Y 3. p 4. q 5. del 7. der 8. dup 9. ins 10. inv 11. / 12. t 13. ter 14. r 15. +/-
- autosome number
- sex chromosomes
- short arm of chrome, petit
- long arm
- deletion of chromosome material
- derivative, structurally rearranged chrom
- duplication of parts of chrom
- insertion of DNA into
- inversion of DNA within
- indicate mosaicism (2 different cell types within one individual)
- translocation (region moved are described after t symbol)
- terminal (or pter, qter)
- ring chrom
- placed before chromo #, addiitons/deletion of whole chromo
Explain Karyotype
- 46, XY
- 47, XX, +21
- 47, XY, +21/46, XY
- 46, XY, del(4)(p14)
- 46, XX, dup(5p)
- 46, XX, inv(3)(p21;q13)
- 46, X, r(X)
- normal male chromosome constitution
- female with trisomy 21
- male c mosaic of trisomy 21 cells and normal cells
- male with deletion at chromosome 4 at short arm designated band 14
- woman with duplication of short arm at chromosome 5
- female with inversion on chromosome 3 between band 21 on short arm and band 13 on long arm
- female with one normal X chromosome and one ring X chromosome
Definition of:
- euploid
- diploid
- triploidy
- aneuploid
- monosomies
- trisomies - consequences of these abnormality?
- human with multiple of 23 chromosomes
- 46 chromosomes
- 69 chromosomes
- does not have a multiple of 23 chromosomes
- 1 copy of a chromosome always lethal if autosomal
- a limited number allow survival - spontaneous abortion due to too many expressed genes in polyploidy, on autosomes, is detrimental to development
What causes polyploidy?
Result from what during maternal meisos II?
Common forms? (3)
what are dignynic & diandric
- fertilization of same ovum by 2 or more sperm
- errors in maternal meiosis II –>egg with diploid # of chromosomes–>fertilized by a sperm with haploid # chrome.
- 69, XXX+69, XXY
- digynic=46 chrom from mom
- diandric= 46 chrom from dad (65%-75%)
What causes aneuploidy?
- prevalance
- common causes
- related to
1 in 300 newborn infants are aneuploid - non-disjunction -More common in eggs > sperm -trisomies due to errors in maternal meiosis I egg suspended in meiosis II -maternal age
Describe non-disjunction in meiotic & mitotic division
nondysjunction in Meosis I -chromosome are different in the gametes nondisjunction Meiosis II -chromosome are identical gametes -both lead to trisomic & monosomic zygote
mitotic –>mosaicism
- one of the cells has no disjunction event during mitosis
- will have mixture of normal and trisomic cells, monosomic usually die off
- all daughter cells with trisomy
- single cells could live with trisomy
- common in tumors
Major Chromosomal Aneuploidy Syndromes Compatible with Live Births
- what is the chromosomal abnormality?
- clinical features?
- why does chrome 13, 18, 21 trisomies occur?
1. patau’s syndrome
2. edward’s syndrome
3. down syndrome
4. turner syndrome
5. klinefeltter’s syndrome
6. Triple X
7. XYY
- trisomy 13
- cleft lip & palate, several CNS anomaly, polydactyly - trisomy 18
- low birth wt, CNS anomalies, heart defects - trisomy 21
- hypotonia, characteristic facial features, developmental delays - monosomy X
- short stature, amenorrhea, lack secondary sexual development - XXY
- small testes, infertility, tall stature, learning problems - XXX
- learning disabilities, no major physical anomalies - XYY
- learning & behavior problems
13, 18, 21 are small chrom. with large sections of heterochromatin (inactive)
- 21 smallest mildest symptoms
- 13 & 18 lead to early death
Structural Abnormalities in Chromosomes describe: 1. pericentric 2. paracentric 3. duplication 4. interstitial & terminal deletions 5. which are inversion vs.insertion vs. duplication? 6. what has genetic lose and which does not?
- 2.
3.
4.interstitial= middle; terminal= end - pericentric & paracentric= inversion
insertion of one part into another chrom. or duplicated from original and insert into original - deletion, isochromosome, microdeletion= genetic loss
- no genetic loss= inversion, reciprocal translocation
What is isochromosomes?
What does it lead to?
- abnormal centromere division
- result in either duplication of p arm or deletion of q arm (iso-p)
- or duplication of q arm & deletion of p arm (iso-q)
- loss of genetic material
Compare & Contrast :
Reciprocal vs. Robertsonian translocation
Reciprocal
- No loss of genetic material
- Carrier usually phenotypically normal; problems with gametes
- The resulting chromosomes are called derivative chromosomes
Robertsonian
- occur between acrocentric (centromere close to the end) chromosomes (13, 14, 15, 21, 22).
- short arms lost, one long arm fused generated.
- genes lost from short arms are rRNA genes, which are duplicated elsewhere in the chromosome
- carriers are phenotypically normal.
- individuals will have a karyotype of 45 chromosomes.
- problems with gamete formation.
Gametes in reciprocal vs. robertsonian translocation
- both have 1/3 for normal function
- the unbalanced monosomy & trisomy gametes not viable for live
What is microdeletion syndromes?
what is lost?
how is it detected?
example?
- Disorders due to a small (< 5 megabases) chromosomal deletion; very complex phenotypes observed
- Multiple genes lost via the deletion–>monosomy for a number of genes
- deletions can only be detected using specific probes to the missing region (FISH)
- Angelman and Prader Willi syndromes are example (15q11)
Indication for prenatal diagnosis include:
Methods to obtain fetal cells for cytogenetic study include
- advanced maternal age (>35)
- Previous child with a chromosomal abnormality
- Family history of chromosomal abnormalities
- Abnormal prenatal screening study
Amniocentesis
Chorionic Villus sampling
Cordocentesis
amniocentesis
when is it perfumed?
risk of what?
how is it performed?
what is being studied?
- Gold Standard
- 0.5% risk of procedure-induced pregnancy loss
- Perform at 15-16 weeks gestation
- Amniotic fluid is obtained using ultrasound to guide the placement of the needle in the uterus
- Remove amniotic cells, culture in lab, do cytogenetics study
chorionic villus sampling
when is it performed?
risk?
how is it done?
- Performed at 10-12 weeks gestation
- Has a 0.5% risk of procedure induced pregnancy loss
- Removed cells are from the placenta (chorion), although they are contaminated with maternal cells. 4. Ultrasound is used to guide needle placement. A separation procedure is required to remove maternal cells from the sample
- Cells are grown in the lab and analyzed
Cordocentesis what is it? when is it indicative to use? how is it done? at what gestation? risk? advantage?
- Umbilical blood sampling; used if inconclusive results are obtained by other procedures
- Ultrasound guides needle into the umbilical artery (obtain blood instead of amniotic fluid)
- Performed after 18 weeks of gestation
- Has a high rate of fetal loss: 1-2%
- Advantage is less time is required to obtain results (blood cells grow more rapidly)
trancriptional initiation & elongation steps (5)
- binding of DNA pol
- separate DNA
- binding of 1 st nuc by base paring
- binding of 2nd nuc & 1st: PPP remains at 5’ end and PPi splits from 2nd nuc
give a general view of a gene from 5’–>3’
-4 important structures
5’–>3’
- regulatory sequence
- promoter
- start point for transcription
- coding region of gene
Promoters–the business end of a gene
- activator & repressors proteins are know as? and what role does it play?
- what are the two promoter consensus sequence?
- transcriptional factors, bind at particular sequence with high affinity that affects transcriptional efficiency
- TTGACA upstream near -30, TATAAT downstream near -10
coding strand vs. template strand
- discuss it’s characteristics and complementary
- which strand is read by RNA polymerase?
- coding strand has the identical sequence informarion to the mRNA
- template strand is the one actually read by RNA polymerase which synthesize a complementary mRNA identical in sequence to the coding strand
Prok promoter recognition involve what protein?
what is this protein bound to?
what transcribe all prok genes?
how many ways can pok terminate transcription?
- alpha protein which only recognizes promoter sequence when it is bound within the holoenzyme
- RNA pol is a multi-subunit enzyme that transcribes all pork genes
- two ways for termination: Rho-dependent or Rho-independent
Compare & contrast
Rho dependent vs. Independent termination of transcription
Rho-dependent
- helicase protein called rho inds RNA-DNA duplex downstream of translation STOP signal (other signal obscure by ribosomes)
- denatures the RNA=DNA duplex using its ATP-dependent unwinding activity
Rho-independent
- termination does not involve other secondary proteins
- specigic G_C rich sequence signal downstream of translation STOP signal causes RNA pol to stall out over an immediately following A/T rich sequence
- DNA duplex is re-established via annealing, expel RNA from transcription bubble
Properties of EUK RNa polymerase I, II, III 1. localization 2. cellular transcripts 3. effect of alpha amanitin
function of:
- rRNA
- miRNA
- tRNA
- How many RNA pol are in prok. ?
Euk:
pol I:
- nucleolus
- 18S, 5.8S, 28S, rRNA
- insensitive
pol II
- nucleoplasm
- mRNA precursors, non-coding RNAs (miRNA) precursors
- strongly inhibited
pol III
- nucleoplasm
- tRNA, 5S rRNA
- inhibted by high concentration only
- important in translation
- …in gene regulation
- — in translation
- PROK.: all RNA species are transcibed by 1 single RNA pol.
compare & contrast Prok vs. Euk cells
- nucleus
- chromosome
- membrane bound organelles
- cell wall
- plasma membrane
- ribosome
- mitochondria for ox phos? translation/transcription? endocytosis?
Prok:
- no nuclear envelope
- single (DNA supercoiled), circular, plasmid
- none
- peptidoglycan cell wall, usually have cell wall
- no carbohydrate, most lack sterols
- 70S
- no mitochondria for ox phis–but in cytoplasmic membrane
- translation & transcription coupled
- no receptor mediated endocytosis
EUK:
- double membrane nuclear envelope
- multiple
- yes
- cell wall in fungi & plants, no petidoglycan
- sterols & carbohydrates
- 80S
- ox phos in mitochondria, transcription in nucleus, protein synthesis in cytoplasm
4 ways bacteria adapt
- streamlined gene expression
- diverse metabolism
- rapid growth
- high numbers
(3&4)= spontaneous mutation rate 10^-6
selection for resistance
- three types of vectors
2. 4 mechanisms of genetic exchange in bacteria
- prok genomes, bacteriophages, plasmids, transposons
2. transformation, transduction, conjugation, transposition
what is a bacteriophage? Describe the bacteriophage: -morphology, -genomes, and l -ife cycles
- is a virus that infects bacteria
- icosahedral, filamentous,
- DNA or RNA, double or single stranded
- virus is genetic material package into virions require host cell for replication
describe the lytic & lysogenic cycle
lytic
- phage DNA attached to bacteria
- inject phage DNA into cytoplasm
- phage DNA direct synthesis of many new phages
- cell lyse and release new phages
- new phage can bind o bacterial cells
lysogenic
- phage DNA attached to bacteria
- inject phage DNA into cytoplasm
- phage DNA integrate into host chromosome
- prophage DNA is copied when cell divides
- exposure to stress such as UV light triggers excision from host chromosome
what is a prophage?
where do you see it, cycle?
what’s episome?
- is a phage DNA integration into host chromosome
- found in lysogenic cycle
- plasmid integrate into chromosome (F+ factor)
- replication of integrated episome is synchronous with host chromosome
bacterial chromosome vs. plasmid
bact chromo.
- circule double stranded DNA
- 3000 gene
- one copy per cell
- highly folded
plasmid
- ciruclar double stranded DNA
- 5-100 genes
- 1-20 copies per cell
what is a transposon found under what condition?
why?
what is the consequences of transposition?
- transposon are never free, they are either found on plasmid or chromosome
- they do not have origin of replication
- a. inactivate genes at insertion site
b. move around gnes necessary for function
c. introduce drug resistance gene
describe transformation
- DNA fragment insert into bacteria
- uptake of DNA into bact. chromosome
- integration by nonreciprocal recombination
or degradation unsuccessful transformation
ie. transformation of plasmid used in rDNA technology
what does transduction requires?
phage
Describe conjugation
-what is HFR (high frequency of recombination?
types of plasmids
- plasmid in once prok transfer over via secretion bridge to another prok cell (filli transfer DNA material)
- the receiver cell recirculate plasmid and recombined fragment
plasmids: F+ factor, RTF (resistance transfer facor),–>episome
HRF- transfer alot of host chromosome.
3 major things in cytosol of prok.
- generate ATP, RNA/DNA, cell wall synthesis
- ribosomes throughout cytoplasms 70S
- DNA supercoiled
4 possible things related to the envelope layers of prok.
-what is the difference between the envelope of gram - and + bacteria?
- cytoplasmic membrane–>phospholipid bilayer + proteins
- cell wall
- capsule
- outer membrane found in gram - bacteria
cytoplasmic membrane of pork. composed of?
-7 fucntions of it
- phospholipids & proteins
1. transport nutrients
2. regulation of gene expression
3. energy generation
4. peptidoglycan synthesis & turnover
5. secretion
6. cell divison
7. sensor mechanisms
functions (5) of cell wall peptidoglycan
- unique to eubacteria
- protect cytoplasmic membrane from osmotic stress environment
- define shape
- cell division
- can cause symptoms in animals (induce inflammation, cytokine release, sepsis)
what are cell wall made of?
how does this affect staining?
possible morphology
compare & contrast peptidoglycan btw gram - & +
- peptidoglycan cell wall=murein= highly crosslinked mesh of peptides & polysaccharides
-NAM & NAG - gram + retain crystal violet color stain due to outer membrane layer
gram - has a counter stain red color - they can be gram -/+ rods, gram -/+ coccus
- Gram + cell envelope
-lipoteichoic acid & teichoic acid
-thicker peptidoglycan layer
-no outer membrane
-no LPS endotoxin activity
-has a lysine-5 gly-NH2+ bridge
-D-ala & L-glu amino acid
-stain crystal violet
-NAM & NAG
Gram - cell envelope -no lipoteichoic & teichoic acid -thinner peptidoglycan layer -outer membrane present -has LPS endotoxin -no bridge -has DAP (diaminopemelic acid) -D-alu, L-glu amino acids -counter stain red -NAM & NAG -
action of beta-lactam antibiotic
what is a penicillin binding protein?
- precursors crosslinked by penicellin binding protein (PBP)–>precurosrs to cell wall
- b-lactam enters cell wall bind PBP
- binding lead to autolysine–>break down preformed cell wall
- b-lactam PBP cannot make cell wall
- cell wall lose integrity–>osmotic stress will effect it
- PBP=transpeptidase
pharmacologica activity of LPS from Gram -
describe the pathway that lead to multi-organ system failure
-endotoxin is not directly responsible for effect of LPS pharmacologic activity
MOSF
- release of endotoxin–>release acute phase cytokines (IL1, 6, TFN-a, platelet activating factor)
- low conc, can be protective (fever, vasodilation, immune & inflammatory response
- high level–>shock & death
- can activate alternative complement pathway, promote high fever, hypotension, shock (vasodilation & capillary leakage), DIC due to activation of blood coagulation pathways
- MOSF
compare & contrast gram +/- by each:
- cell wall (peptidoglycan)
- outer membrane
- LPS
- endotoxin lipid A
- teichoic acid
- lysozyme
- antibacterial activity of penicillin
- capsule
- exotoxin production
Gram+ vs. Gram
- thicker/thinner
- none/yes
- n/y
- n/y
- often/absent
- sensitive/resitant
- more susceptible/more resistant
- sometimes/sometimes
- some strain/some strains
phenotypic variation arises from?
which is more frequent? why?
what change occurs?
- genotypic variation called polymorphism
- Variation in DNA sequence in greater magnitude in frequency than variation in protein sequence, which polymorphism are responsible for many phenotypes. More DNA polymorphism outside the protein coding sequences
- IN both DNA & protein polymorphism, it occurs when there is a change in the base pair sequence
phenotypic variation arises from?
which is more frequent? why?
what change occurs?
- genotypic variation called polymorphism
- Variation in DNA sequence in greater magnitude in frequency than variation in protein sequence, which polymorphism are responsible for many phenotypes. More DNA polymorphism outside the protein coding sequences
- IN both DNA & protein polymorphism, it occurs when there is a change in the base pair sequence
5 types of DNA polymorphisms summary
- RFLP- restriction fragment length polymorphism
- SNP- single nucleotide polymorphism. most common
- VNTR- variable number of tandem repeats, mini satellite
- STR- short tandem repeats (Microsatellites)
- CNV- copy number variation
basic principle for detection of DNA variability is differences in size or sequences of fragments
genetic drift
substantial departure of observed allele frequency from expected frequency from generation to generation due to small population size
gene flow
change of allele frquencies due to mixture and migration of populations
what is the amount of variation of polymorphism btw two individuals?
most variation in human traits is due to DNA polymorphism. 1 million polymorphic differences btw 2 people
1/3000 base pairs