genetics final exam review Flashcards
what is the hardy weinberg equation
p^2+2pq+q^2=1
2pq= frequency of heterozygous genotype
p^2 = frequency of homozygous dominant genotype
q= frequency of reccessisve allele
q^2 = frequency of homozygous reccesive
p^2 = frequency of homozygous genotype
what are the five assumptions of hardy weinberg equilibrum
random mating
no change in mutattion rate
no migration
no artificial selection
large population
what is the founder effect vs bottleneck drift
the founder effect occurs when population originates from smaller populations.
example: splitting of a small population to establish a colony
A genetic bottleneck occurs when a population is greatly reduced in size, limiting the genetic diversity of the species.
example original population composed of red and blue and a disaster happens causing a few red indivisuals to survuve and pass their genes to a new population.
disruptive selection
Selection for phenotypes at both extremes. Intermediates are selected against.
stabilzing selection
selects for intermediate phenotypes, with those at both extremes being selected against.
directional selection
phenotypes at one end of the spectrum become selected for or against, usually as a result of changes in the environment.
Ex: beak sizes in finches during dry years increased due to strong selection
in hardy weinberg equilibrum a population is evolving if
the allele frequencies change between generations
what is cystic fibrosis
thick mucus, lungs become clogged with mucus. the mucus eventually harbors bacteria and they have recurrent respiratory infections, is autosomal recessive
inability of chloride ions to cross epithelial cells (salivary, mucus and sweat glands, and pancreas)
what is a species
a species is a group of actually interbreeding organisms reproductively isolated
in nature from all such other groups.
what is speciation
speciation transforms parental species or divides single species into two or more seperate species.
what is genetic divergence and genetic drift
genetic divergence of populations can reflect action or natural selection, genetic drift or both
genetic drift is when a random event causes an increase or decrease in allele frequency
what is macroevolution
macroevolution is genetiic changes that result in reproductive isolation between two species
and leads to formation of species
what is the difference between prezygotic and postzygotic barriers
prezygotic barriers prevent mating from taking place due to behaivoral isolation and postzygotic barriers create reproductive isolation even when two members of two populations mate with each other because zygotes may be inviable and hybrids may be sterile .
what is phylogeny
genetic differences among PRESENT DAY SPECIES that can be used to construct their evolutionary history
define a phylogentic tree
a phylogentic tree is branvches that represent lineage over time and monophyletic groups consist of ancesteral groups and species.
what is sickle cell anemia
r genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape. Is autosomal recessive
what is hemophilia
an x linked blood linked clotting disorder
turnder syndrome is an example of what
turner syndrome is an example of a monosomy trait
transition mutation
an example of a transition mutation is when a purine replaces a purine
what is genetic drift
genetic drift are random fluctations in allele frequencies by change alone in small populations
what is natural selection
natural selection is a difference among indivisuals in survival or reproduction rate.
metacentric
when the centromere is located at the middle of the chromosome
penetrance
the percentage of indivisuals that sow at least some degree of expressio of a mutateed gene at the phenotype
nucleosome
is dna entwined around a octet of protiens
discondoradant
a pair of momozygotic twins where one is afflicted with osteoporosis and one is not
why is rna primer considered essentail during dna synthesis
the enzyme requires a free 3 oh group
in drosophila sex is determined by
the ratio of the number of x chromosomes to the number of autosomes
what are the post translational modifications
Translation generates a polypeptide chain. Modifications May be needed for a polypeptide chain to be functional to act as a protein.
1. Removal of N-terminus and C-terminus amino acid
2. Individual amino acids are sometimes modified
3. Glycoproteins
4. Cleave polypeptide chains
5. Signal sequences are removed
6. Polypeptide chains interact with metals
prb
inactivates the transcription factor e2f
frameshift
an insertion or deletion of a base that alters the reading frame
hunington diseases
a progressive neurodegenerative disorder causing lack of muscle. Is fatal. Is autosomal dominant. Is an example of a lethal allele. Although the individual will die, the effects are usually later in life.
marfan syndrome
A connective tissue disorder manifested by changes in the skeleton, eyes, and cardiovascular system. An autosomal dominant disorder
tay sach disease
A lipid storage disorder which is autosomal recessive.
-hexoaminidase is the enzyme involved in lipid metabolism and the enzyme is affected in this disorder.
-symptoms: neurodegenerative, psychosis, motor development, loss of voluntary motor skill
klinefelter syndrome
=males with an extra X chromosome, with 47 chromosomes in total. (47, XXY)
-phenotypes: incomplete sexual development (rudimentary testes and prostate), long limbs, large hands and feet, gynecomastia-breast tissue development
can see 48, XXXY or 48, XXYY or 49, XXXXY If nondisjunction happens more severely
jacobs syndrome
condition when a male has an extra Y chromosome. (47, XYY).
-results from father giving an extra Y in meiosis
-96% of males will be phenotypically normal
-modest phenotypes: increase in height, acne, and minor speech/ reading problems, personality disorders
triplo -x aneuploidy
a condition when a female has three copies of the X chromosome. (47, XXX)
-few modest effects on phenotype include tallness, menstrual irregularities and slight impact on intelligence.
neurofibromatosis
genetic disorder with multiple benign fibrous tumors that grow anywhere in the nervous system including the brain, spinal cord, and peripheral nerves. Is an autosomal dominant disorder.
reproductive isolating mechanisms
biological barriers that prevent or reduce interbreeding between populations.
Can be ecological, behavioral, seasonal, mechanical, or physiological.
griffith experiment
heat killed virulent bacteria and transformed the living nonvirulent bacteria.
avery maclead mcarthy
proved dna is the agent of transformation
hersey chase experiment
used radioactive phosphorous for dna and radioactive sulfur for protein to lable phage components and proved dna is the genetic matieral
telomerase
an enzyme that extends the end of a dna template and allows dna to be fully synthesized without shortening
what do dna polymerase 1 and 2 do
DNA polymerase I and II function in correcting mistakes made by DNA polymerase III . They detect and remove non complementary base pairs and have exonuclease activity in 3’ to 5’ direction.
rosalind franklin and watson crick
Used x-ray crystallography to study DNA structure. This technology aims to form a crystal of the molecule, mimicking its environment.
-this image shows the following features:
1. Right handed double helix
2. Chains antiparallel C-5’ to C-3’
3. Bases are 3.4 A apart
4. 10 bases per turn
5. Major and Minor grooves
6. Helix 20A in diameter
james watson and francis
developed the molecule model of DNA using information from many researchers
erwin chargaff
Discovered that DNA composition varies and created rules . There’s always equal amounts of purines to pyrimidines.
-Purines = pyrimidines
-(A+G) = (C+T)
- % of G+ C does NOT equal % of A+T
ligase
enzyme joins Okazaki fragments and seals other nicks in the sugar-phosphate backbone.
dna ploymerase 3
responsible for the 5’ to 3’ polymerization essential to in vivo replicatio
ozaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
dna ligase
Enzyme that joins two fragments of DNA to make a single fragment. It pastes together the Okazaki fragments together from the lagging strand.
leading strand vs lagging strand
The new complementary strand synthesized continuously along the template strand in the 5’ to 3’ direction is the leading strand.
the strand that is synthesized away from the replication fork , in pieces. Is discontinuous is the lagging strand.
dna topoisomerase
Enzyme that relieves overwinding strain ahead of replication forks on DNA during replication.
helicase
An enzyme that untwists the double helix of DNA at the replication forks.
middle repetitive dna
Consists of tandem repeats and interspersed retrotransposons
vntrs
variable number of tandem repeats. Are sequences 15-100bp in length which are repeated one after another in tandem. Are found within and between genes and often referred to as minisatellites
satellite dna
Variable DNA in short repeated sequences. Is a type of highly repetitive DNA.
Ex: CEN region, telomere
highly repetitve dna
DNA that consists of relatively short sequences that are repeated numerous times.
-satellite DNA is a type
messelson stahl experiment
proved that semi conservative replication is the nose used by bacterial cells to produce new DNA molecules.
-grew E.coli in different nitrogen dense mediums
sines
short interspersed elements that make up 13% of human genome. Example is the alu family which can
LINES
long interspersed elements that make up 21% of human genome. Are longer than 500 BP in length. Example is the L1 family in humans.
STRs
short tandem repeats. Are a group of tandemly repeated sequences smaller than 15bp in length. site. Also referred to as microsatellites.
interdispersed transpoons
short or long DNA sequences that can insert itself at a new location in the genome.
Types: SINES (less than 500 BP), LINES (longer than 500 BP)
describes the types of rna
messenger rna carries genetic information from DNA to the ribosomes
transfer rna Carries amino acids to the ribosome during translation
ribosomal rna type of RNA that makes up the major part of ribosomes, which helps to translate mRNA into protein
prader will syndrome
Occurs when a a deletion is inherited paternally.
-symptoms: short stature, mental retardation, low muscle
-prognosis: do well in monitored environments
angleman syndrome
Occurs when a deletion is inherited maternally.
-clinical features: feeding problems, delay in milestones, absent speech, severe learning disabilities, epilepsy, lack of pigmentation, laughter
-referred to as the happy puppet
-can never live on their own
variable expressivity
Says there is a range of expression of mutant genotypes.
Ex: FF or Ff forms of deafness. Different individuals with the same genotype may express it differently. Some may show mild, moderate, or profound forms of deafness.
incomplete penetrance
not all individuals with a disease-associated genotype will show the disease phenotype.
Ex: A person who had polydactyl may not be fully penetrant on that gene.
DD or Dd~ 80%~ polydactyl
DD or Dd~ 20%~ no polydact
x linked dominant versus x linked recessive trait
x linked dominant trait this type of trait is expressed in females with one copy
-males are often more severely affected because they don’t have another normal X to balance it out
his type of trait is always expressed in males
-affected males: inherited the trait from the mother are x linked reccesive triats
males versus females
females -have two X chromosomes (XX) that are each inherited from one parent.
-three possible genotypes: X⁺X⁺, X⁺Xᵐ, or XᵐXᵐ
males ve one X chromosome that was inherited from the mother are hemizygous only have one x chromosome
codominance versus incomplete partial dominance
both alleles are being expressed in a heterozygote
-2 distinct, detectable gene products exist
incomplete partial dominance when both alleles of a gene at a locus are partially expressed, often resulting in an intermediate phenotype. a blend
Ex: red and white parent flowers producing pink offspring in F1 generation
phenylketonuria
a disorder related to a defective recessive gene on chromosome 12 that prevents metabolism of phenylalanine (an amino acid)
ataxia Telangiectasia
an AR disease due to defect in DNA repair enzymes. Is an autosomal recessive disorder.
familal hypercholesteolemia
metabolic disorder that is caused by defective or absent receptors for LDLs on cell surfaces, that is inherited as an autosomal dominant trait.
what is the definition of transcription and translation
(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA
Translation (genetics) the organic process whereby the DNA sequence in a gene is copied into mRNa
meosis 1 vs meiosis 2
Meiosis 1: separation of homologous chromosomes
Meiosis 2: separation of sister chromatids
mitosis
Cell division where chromosomes are copied and distributed that each daughter cell receives a diploid set of chromosomes identical to the parent cell
meoisis
Cell division associated with gamete formation where the cells produced receive a haploid set of chromosomes
law of independant assortment
Two genes on different chromosomes segregate their alleles independently.
-the inheritance of one gene
independant product assortment law
When two independent events occur simultaneously, the combined probability of 2 outcomes is equal to the product of their individual probabilities.
ancondroplasdia
A form of dwarfism that is autosomal dominant. There’s a 50/50 chance of passing it on.
fragile x syndrome
most common form of inherited mental retardation. Is a result of the X chromosome having a fragile end (a segment more prone to breakage)
gene: FMR-1 shows gene anticipation and tri nucleotide repeat.
patau syndrome and edwards syndrome
Trisomy 13. “47, +13” patau
-Is lethal
-major abnormalities-microcephaly, open sutures, heart, kidney, neurological, cleft lip/palate, polydactyl, clenched fists
-increase in father’s age increases the risk
familal down syndrome
Caused by a Robertsonian translocation in which the long arm of chromosome 21 is translocated to another chromosome; tends to run in families.
-chromosome 14 and 21 create a translocation carrier
-will appear phenotypically normal but have 45 chromosomes
robertonsian translocation
When two nonhomologous acrocentric (having centromere close to the end) chromosomes break at the centromere and long arms fuse
pericentric inversion
inversion that includes the centromere in the inverted sequence
allyopolypoidy
polyploidy resulting from contribution of chromosomes two closely related species or different species
autopolyploidy
an individual that has more than two chromosome sets that are all derived from a single species.
Failure of segregation.
2. Cell never divides and goes directly to interphase.
3. Dispermy
4. Experimental conditions
autotriploid
A 3n polyploid that has one extra set of chromosomes, identical to the normal haploid complement of the same species. They produce unbalanced gametes and cannot propagate sexuall
autotetraploid
a 4n polyploid that has two extra sets of chromosomes, identical to the normal haploid complement of the same species. They produce balanced gametes and can propagate sexually.
dispermy
simultaneous fertilization of egg with two sperm. Can cause Triploidy. Extremely rare!!
edwards syndrome
“47, +18”
-lethal
-characteristic: clenched fists, severe heart defects, low set ears, receding jaw, physical and mental problems, small head, etc
-higher maternal age increases the risk
down syndrome
7, +21”
=having 3 copies of the 21st chromosome
-was the 1st chromosomal abnormality discovered
-phenotypic characteristics : epicanthic fold on upper eye, flat face, simian crease on palm, large tongue-open mouth, intellectual disability, congenital heart defects, prone to leukemia
-lovable, happy
-high survival rate
-higher maternal age increases the risk
cri chu dat syndrome
46, 5p segmental deletion”
=deletion of part of the p arm on chromosome 5
-is a partial Monosomy/ deletion
-characteristic: infant’s cry sounds like a cat at birth
-symptoms: cry (larynx, glottis development), GI, cardiac problems, intellectual disability
-is sporadic, meaning it’s not
testes determining factor
protein encoded by a gene in the SRY that triggers testes formation
presenced of a y chromosome
The presence of a Y chromosome or the presence of the SRY gene on the Y chromosome can determine sex.
sry region
sex determining region on Y-chromosome located just under the PAR gene. Activates at the 6th week in development in utero. When translated, it produces a protein called the TDF.
msy region
male specific region of the Y chromosome that makes up the majority of the Y chromosome.
Within this large region, there is : heterochromatin, euchromatin, and an SRY region.
par region
pseudoautosomal region)= this region has genes similar to X chromosome genes. Have one on each tip of the Y chromosome. It can undergo recombinant crossing with parts of the X chromosome.
turner syndrome
=condition when an individual has only one X sex chromosome and 45 total chromosomes. (45, X)
-absence of a Y leads to development as a female
-diagnosed through a karyotype
-phenotypes: short stature <4’10”, webbing at the back of the neck, incomplete sexual development (sterile), hearing impairment, heart disease, aorta defects.
heterochromatin vs eurochromatin
heterochromatin highly condensed chromatin that lacks functional genes
eurochromatin highly condensed chromatin that lacks functional genes
klienfelter syndrome
=males with an extra X chromosome, with 47 chromosomes in total. (47, XXY)
-phenotypes: incomplete sexual development (rudimentary testes and prostate), long limbs, large hands and feet, gynecomastia-breast tissue development
-some cases not diagnosed until fertility problems
small nuclear RNA
small RNA molecule of 100-200 nucleotides that participates in RNA splicing and is an essential component of the spliceosome.
-are complexed with proteins to form small nuclear ribonucleoproteins (snRNPs or snurps).
enhancers
DNA sequence that aides in allowing RNA polymerase to bind to the promoter region and recognize there is a gene to be transcribed
cis acting elements
Sequences or elements that are part of the gene on the same side/ are adjacent parts of the DNA molecule
knockout genes
A gene that takes the place of another gene, creating a mutation so the protein does not get made. Generates a null allele
muscular dystrophy
group of hereditary diseases characterized by degeneration of muscle and weakness.
-DMD= x-linked, severe heart and lung issues, can be fatal by early 20’s. Because of a Frameshift mutation, null allele results.
transposable elements
jumping genes” that can move within and between chromosomes inserting themselves into various locations within genome.
xeroda pigmentosum
a rare recessive genetic disorder that predisposes individuals to severe skin abnormalities, skin cancers, etc. because individuals can’t protect against UV light.
photoreactivation repair
-is a repair mechanism for UV damage
-is the prokaryotic mechanism to reverse pyrimidine dimers
-used photoreactivation enzyme (PRE)
nucleotide excision repair
type of excision repair that Repairs legions in the DNA like the UV-induced pyrimidine dimers.
base excision repair
type of excision repair that corrects DNA with a damaged DNA base.
-DNA glycosylase is the enzyme that recognizes the mismatched base. It then cuts the bond between the base and sugar, creating an apurinic site or apyrimidinic site
sos repair system
is a last resort repair mechanism to minimize DNA damage because it allows replication to occur without fixing the problem.
post replication repair
=is a last resort repair mechanism to minimize DNA damage because it allows replication to occur without fixing the problem.
proofreading
dNA polymerase has capability to use exonuclease activity to repair mistakes in the newly created strand after transcription
gain of function
a mutation that confers new or enhanced activity on a protein, may cause the protein to have a slightly different function
loss of function mutation
Mutation which results in a non-functional or missing gene product. Is called a “null mutation
frameshift mutation
mutation that shifts the “reading” frame of the genetic message by inserting or deleting a nucleotide. (Unless the insertion/ deletion is a multiple of 3).
transverssion mutation
An example of a point mutation is the single base change in the hemoglobin gene that causes sickle cell anemia.
-T becomes an A
-pyrimidine becomes a purine
silent mutation
A mutation that changes a single nucleotide, but does not change the amino acid created. Mutation is hidden
nonsense mutation
A mutation that changes an amino acid codon to one of the three stop codons (UAG, UAA, UGA), resulting in a shorter and usually nonfunctional protein.
missense mutation
nucleotide-pair substitution that results in a codon that codes for a different amino acid
point mutation
mutation that changes a single base/ single nucleotide.
spontaneous mutation
random change in the DNA arising from errors in replication that occur randomly.
induced mutation
a mutation caused by external agents such as mutagenic chemicals or radiation in the environment.
-mutagens
-carcinogens
germline vs somatic mutation
germline mutation mutation that occur in gamete cells. Can be passed on in generations.
somatic mutation A mutation that occurs in the body cells. Cannot be inherited.
characteristic of genetic code
dNA template serves as the template for mRNA
-codon (3 mRNA bases)
-unambiguous: each codon codes for 1 amino acid
-degenerate (more than one codon codes for an amino acid)
-start/ stop codon
-commaless -no breaks
- is non-overlapping
-universality of DNA
degenerate
he genetic code is __________, meaning different codons can code for the same amino acid.
commales
The genetic code is __________, meaning that once the reading frame starts, it does not break until a stop codon is reached.
rna polymerase
Transcription is mediated by this enzyme. It separates the DNA and creates RNA without any primers needed first. It synthesizes RNA, creating Phosphodiester bonds.
quartenary structure
protein consisting of more than one amino acid chain. Not all proteins have this.
teritary protein structure
The 3D conformation of a protein.
-has disulfide bonds that reinforce the structure
secondary protein structure
occurs when the sequence of amino acids are linked by hydrogen bonds which connect portions of the backbone in a repetitive pattern.
primary protein structure
linear sequence of amino acids
termination of translation
occurs when a stop codon/termination codon/ nonsense codon in the mRNA reaches the A site of the ribosome. The polypeptide chain is done being extended.
elongation of translation
- More charged tRNA enters the ribosome through the A-site.
- Peptide bond forms by an enzyme known as peptidyl transferase.
- A shift occurs where the ribosome moves from 5’ to 3’. Shifts by 3bp. Requires elongation factors and GTP.
- More charged tRNA enters the A-site and more elongation occurs until stop codon is reached
iniation of translation
mRNA binds to the small subunit along with initiation factors
-initiator tRNA binds to mRNA codon in the p-site to form the initiation complex
-large subunit binds to the small subunit and the Monosome complex is formed. tRNA enters through the A-site
3 steps of translation
- Initiation- control of transcription is regulated by transcription factors -no primer needed
- Elongation- RNA polymerase adds nucleotides to the growing RNA
- Termination- sequences in the DNA prompt the RNA polymerase to fall off, ending the transcrip
transacting elements
regulatory proteins that bind to such DNA sequences to act on the DNA, like transcription factors.
transcription factors
Proteins that regulate the initiation of transcription. They signal for where RNA polymerase must bind.
Ex: TATA-binding protein (TBP): binds to the TATA bo
iniation of transcription
-begins upstream of the gene in a region called the promoter
-the promoter recruits TATA protein , a DNA binding protein, which in turn recruits other proteins
-transcription factors are recruited
-when a complete transcription complex is formed, RNA polymerase binds and transcription begins
post transcriptional modification of rna
addition of capping nucleotide at the 5’ end
-addition of poly A tail to 3’ end
-splicing occurs, removing introns
introns vs extrons
introns sequence of DNA that is not involved in coding for a protein, are removed in processing
expressed sequence of DNA; codes for a protein
riboenzyme
rNA capable of splicing themselves; are autocatalytic. Will splice out introns and ligate them back together.
tata box
A promoter DNA sequence crucial in forming the transcription initiation complex. Is rich in thymine and adenine residues
translation
synthesis of protein from the mRNA template. Happens in the ribosome (has two subunits). When large and small subunit come together, they can activate this process to occur/ form an active
rRNA
type of RNA that makes up the major part of ribosomes. Helps translate mRNA into protein
amino trna synthease
An enzyme that joins each amino acid to the appropriate tRNA to charge the tRNA.
-is specific for its amino acid
-used energy in the form of
a site
Amino-acyl tRNA site; the site on a ribosome where the tRNA can enter the ribosome.
iniation factors
Proteins that function in binding the small subunit of the ribosome during initiation of translation to start the polypeptide chain can be elongated
elongation factors
Protein that function in bringing the tRNAs into the ribosome through the A-site so the polypeptide chain can be elongated
tumorigenesis
The process by which normal cells become cancerous by developing mutations. These mutations give the cell an advantage. Cancer cells will outcompete/ outdivide other cell
dna methylation
The addition of methyl groups to bases of DNA after DNA synthesis; silences the gene because methyl groups interfere with the binding of transcription factors. RNA polymerase cannot bind.
-the enzymatic reaction can easily be reversed
trytophan
-it serves as a co-repressor and binds to the repressor protein,
7 hallmarks of cancer
- Growing uncontrollably
- Accumulation of mutations
- Metastasis
- Avoiding detection from the immune system
- Evading apoptosis
- Angiogenesis
- Immortality
ubiquitin
a small protein that tags other proteins for degradation by proteolytic enzymes
negative control
gene expression occurs unless it is shut off by some form of a regulator molecule. Is on, unless turned off
positive control
Transcription only occurs if a regulator molecule directly stimulates RNA production. Is off, unless turned on
Transcription only occurs if a regulator molecule directly stimulates RNA production. Is off, unless turned on
negative control
continous variation
Traits that have many classes and variations
Ex: weight, height, skin pigmentation
discontinous variation
Distinct classes of traits.
Ex: blood type, pea shape
skin pigmentation
A trait controlled by multiple genes. An example of quantitative trait example. Environment and genetics play a role.
familal adenomatous polyposis
heredity condition in which multiple polyps form in the colon and rectum, predisposing to colorectal cancer
polyps
initially with all cancers these clones of cells form. Aren’t necessarily cancerous to begin with
rb1 gene
The tumor-suppressing gene that controls the G1/S transition in the cell cycle in all cells. The protein is called pRB. Without pRB, cell division is uncontrolled.
sporadic
When two spontaneous mutations must occur for the cancer to develop we classify it as.
p21
When there is DNA damage, p53 will release ________ to inhibit cyclin dependent kinases to keep the cell in G1.
DK inhibitor that works to block CDKs/cyclins to keep RB active (holding E2). This will not allow cells to move to S phase.
p53
A tumor supresor gene that has the function of preventing cell division. Is an important protein that keeps the genome intact; “guardian of the genome”.
-is a transcription factor, so it controls the transcription of proteins
-it transcribes genes necessary for DNA repair
-can cause cell cycle arrest and apoptosis of DNA is not repaired
gain of function
the Ras protein is part of a normal transduction pathway. It switches between active and inactive states and tells the cell to divide. If it is always active, a _____________ mutation may occur because the cell will constantly be told to divide.
-2 alleles make Ras
What are the 3 ways a proto-oncogene can become an oncogene?
p.oint mutation
o. ver expression
t.ranslocatoin
p.o,t
proto-oncogens
Cancer causing genes disrupt control of the cell cycle. One way is by promoting cell division.
=these genes work to promote division. When it mutates, it is called an oncogene (cancer causing form of the gene).
-has a “gain of function”
sporadic cancer
Cancer occurs in somatic cells. It spontaneously arises after acquiring 2 mutations.
capsases
responsible for enzymatic cell death in apoptosis because they cleave the DNA.
signal transductiion
Pathway that allows cells to communicate. The pathway is defective in cancer cells, so the cancer cells do not signal each other to stop dividing.
cdk cyclin
he regulatory molecule of checkpoints. The cyclin must bind to a CDK.
-CDK= Is a cyclin with a specific kinase (kinase only works when it’s bound to its cyclin).
malignant tumor
An abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor.
small inerfering rna
short, double stranded RNA molecules used in RNA interference. They degrade particular mRNA for gene silencing. Are used in lab to study effects of a protein not getting made
rna interfernece
inhibition of gene expression by RNA molecules seen in animals.
rna silencing
A way to control gene expression after transcription has taken place. If the cell no longer needs a protein, it can get rid of a message.
-short RNA molecules regulate expression by repressing translation, degrading mRNA, alerting chromatin structure
inducible expression
A cell recognizes it needs to make a protein is a certain function is needed. Cells are efficient. Something in the environment will cause a protein to be made
consitutive expression
some genes are constantly being expressed, because we need the function all the time.
repressible expresssion
Something in the environment represses/ shuts down gene expression
alloexteric mlecule
This is how lactose activates gene expression and why the repressor protein is referred to as an _____________(can take on different conformations)
glucose is present lactose cannot be broken
Positive control of the lac operon:
If glucose is present in the body..
-cAMP levels decrease because glucose inhibits Adenyl cyclase from converging ATP to cAMP
the cis-acting promoter region is extensive and has these 3 conserved promoter sites which are necessary for binding of the trans-acting elements
TATA box, CAAT box, GC box
RNA-induced silencing complex (RISC)
the complex that mediates RNA interference. Is made up of multiple proteins. It degrades one of the strands of mRNA but cutting the mRNA so mRNA will naturally be degraded by the cell. So the gene will be silenced.
microRNA
small, single-stranded RNA molecule of 20-25 nucleotides that block translation from occurring. It associates with one or more proteins in a complex that can degrade or prevent translation of an mRNA with a complementary sequence by pairing with a 3’ untranslated region or other mRNAs.
Li-Fraumeni Syndrome (LFS)
Inherited TP53 mutations: 70% patients have p53 mutations
A hereditary cancer predisposition syndrome. Causes cancer at a very young age.
e2f
cDKs phosphorylate Rb, in which a conformational change releases ___________.
=this is a transcription factor necessary for DNA synthesis and allows for synthesis to take place.
basic leuine zipper
common motif found in the DNA-binding region of transcription factors in eukaryotic genes. Is made up of 4 leucines that form a helix. Has dimers. Leucines hold together like a zippe
zinc fingers
a common motif found in the DNA-binding region of transcription factors in eukaryotic genes. Has loops that interact with DNA and bind to specific sequences.
helix turn helix
common motif found in the DNA-binding domain of transcription factors found in eukaryotic genes. Is part of a much larger domain of protein.
-is a homeobox (180bp)
—has a homeodomain (60bp) that forms it
—has basic aa-conserved sequences
—2 alpha helices
structural motifs of dna factor binding proteins
. Helix-turn-helix (HTH)
2. Zinc Fingers
3. Basic Leucine Zipper (bZIP)
eukaryotic gene regulation
- Greater amount of DNA
- Multiple Chromosomes
- Transcription in nucleus/ Translation in cytoplasm
- Post-transcriptional processing/ Post-translational processing
- mRNA half-life is extended in eukaryotic cells
- Multiple types of cells, each regulating proteins differently
adenyl cylase
An enzyme that converts ATP to cyclic AMP in response to a chemical signal.
cap camp complex
formed by joining the catabolite activator protein to cAMP. This cooperative binding complex allows RNA polymerase to work.
camp
cyclic adenosine monophosphate. Is generated by taking ATP and turning it into this. Adenyl cyclase is the enzyme that helps this process
operon
genes that are clustered together with the same function
post-trasncriptional level
At what level are eukaryotic genes most regulated
heriabilty
the proportion of the total phenotypic variation that is due to genetic differences in a particular environment
brooad sense heriabality
the proportion of the total phenotypic variation that is due to genetic differences in a particular environment vg/vp
narrow sense heribality
the proportion of the total phenotypic variation that is due to genetic differences in a particular environment va/vp
benign tumor
a mass of abnormal cells that remains at the site of origin
cancer
is a multi-step process
-a mutation occurs allowing a cell to undergo cell division when it would not normally divide.
multifactoral
quantative traits
Traits Controlled by 2 or more genes. Have an additive/ synergistic effect.
polygenic trait
trait controlled by two or more genes. Would fall into the category of complex or multi factorial traits . Ex: cancer, weight
continous trait
Polygenic traits that do not fall into discrete categories. They instead have a range of phenotypes
meristic trait
are polygenic traits in which the phenotype is recorded by counting whole numbers.
Ex: how many heart attacks, number of eggs paid by a chicken each year.
additive allele
Describes an allele that yields twice the phenotypic effect when two copies are present at a given locus than occurs when only one copy is present
polygenetic inheritance
agriculture: height, weight, size, yield in crops, beef/milk production
-human: skin pigmentation, intelligence, predisposition to disease
-complex/ multifactorial trait: environmental factors, multiple genes
oncogene
A proto-oncogene that has been mutated or abnormally expressed and contributes to yeh development of cancer
proto oncogenes
encode transcription factors that stimulate expression of other genes, signal transduction of molecules that stimulate cell division, and cell-cycle regulators that move through the cell cycle
cdk cycln complex
cyclin binds to a CDK, triggering this complex which selectively phosphorylates and activates other proteins that in turn being about the changes necessary to advance the cell though the cell cycle.
rna interfernce
A form of sequence-specific translational regulation that regulates gene expression by degrading specific mRNA or by blocking its translation into protein. Is a gene silencing mechansim
concordance
A form of sequence-specific translational regulation that regulates gene expression by degrading specific mRNA or by blocking its translation into protein. Is a gene silencing mechansim
discordance
When one twin expresses the trait and the other does not.
-these twins are less likely to participate in twin studies
concordance rates
likelihood that both twins exhibit the same trait/ disease
dizygotic twins
Twins who are formed when two separate ova are fertilized by two separate sperm at roughly the same time. ( fraternal twins.)
monozygotic twins
twins who originate from one zygote that splits apart very early in development (identical twins)
artificial selection
twins who originate from one zygote that splits apart very early in development (identical twins)
alternative splicing
Control of gene expression after transcription has occured.
-alternative splicing
-mRNA stability: half life of mRNA is increased by adding caps, will eventually be degraded
-recruiting degrading (ex: ubiquitin) or stabilizing complexes
typees of expression
Inducible expression
Enzymes are only produced when specific chemical inducers are present
Repressible expression
The presence of a specific molecule inhibits gene expression
Constitutive expression
Enzymes are produced continuously, regardless of the chemical makeup of the environment
cap vs camp
catabolite activating protein (CAP)
helps activate expression of the lac operon, but is able to inhibit expression when glucose is present. This inhibition is called catabolite repression.
cyclic adensosine monophosphate (cAMP)
In order to bind to the lac operon promoter region, CAP must be bound to _________
adenyl cylase vs trytophan
adenyl cyclase
catalyzes the conversion of ATP to cAMP.
-glucose inhibits this molecule, so when glucose is present more lactose will not be broken down
Trypotophan
This operon is a Repressible gene system in E.coli. In the presence of __________, the repressor binds to the regulatory region of this operon and repressed transcription initiation.
