Genetics Exam 4 - Review Flashcards
Start codon
AUG
Kozak’s Rule
Eukaryotic binding region / sequence that helps with initiating translation
-6 to +4
-3 to +4
What is the secondary structure of proteins
Intramolecular hydrogen bonding and helix and binding peptide sheets (alpha helix and beta sheets)
16s subunit of the ribosome
subunit of ribosome that deletes the wrong tRNA
proofreading
Shuine-Dalgrano Sequence
For bacteria, facilitates the binding of mRNA to the ribosome
Describe the sites within the ribosome (APE)
Looks more like EPA
A - tRNA comes in
P - adding to polypeptide chain
E - exit
Describe translation
tRNA that is charged wtih an anti-codon comes in the A site binds to the anticodon and codon combine
A is approved
If approved, it is attached to the P polypetide chain
E will release it and almost immediately after it will begin to fold into secondary > tertiary > quarteria
DNA methylation
STOP
Increases compaction of DNA making it transcriptionally inactive by preventing gene expression
DNA Acetylation
GO
Decreases compaction of DNA making it more active transcriptionally increasing gene expression
Antisense RNA
Forms the double stranded RNA that PREVENTS TRANSLATION if its complimentary counterpart; physically unable to leave the riboosome
Constitutive
Continously producing a substance for constant level of expression (ON OR OFF)
Ex. Lac operon will consistently be repeated
Stem Loops 3-4
Turns off the trp operon
Stem loops 2-3
Turns on the trp operon
Promoters
Attract RNA polymerase to transcribe genes
Terminators
End transcription genes of remaining RNA polymerase
Operators
Control box of the operon is the site where the receptor binds
What makes up an operon
Other genes > Promoter > Operator > Genes to transcribe > Terminator
Lac operon binds to the repressor and removes it so that the polymerase can continue to transcribe genes
Explain the conditions that turn on the Lac Operon
Glucose is low and lactose is high
Explain what happens in the trp operon
Turns on the trp operon , there needs to be low tryptophan (co-repressor) for the operator, only turned on when needed
What does inducible mean
Usually has an inducer element, needs certain molecules to be induced
What causes negative feedback
Usually has a repressor element
A > B > C > D > FInal product
D can go back at the end and help to repress areas again (after A or B or C)
Activator
proteins that bind to enhancer regions
Repressors
Proteins that bind to silencers
Silencers
Where the repressors bind
Enhancers
Where the activators bind
Epigenetics
The study of mechanisms that lead to change in gene expression that can be passed from cell to cell and are reversible, but do not involve a change in the sequence of DNA (simply allowing expression or not)
Genomic imprinting
Process of silencing genes through DNA methylation and is a form of epigenetic
Chromatin remodeling complexes
Change nucleosome orientation usually ATP - dependent proteins
Require energy to recognize and restructure
Euchromatin
Transcriptionally active DNA (open chromatin)
Not stained during interphase
Heterochromatin
Transcriptionally inactive DNA (closed chromatin)
Stained during cell cycle
Where does regulation of gene expression occur
It can be regulated in every single area
Transcription, Translational and in Proteins
What is transcriptional regulation
Regulated the conversion of DNA to RNA
What is the translation regulation
Regulation the conversion of RNA to proteins (ribosome to RNA)
What is post-transcriptional regulation?
Regulation after transcription but after translation (5’ Cap Poly A Tail)
What is post-translational regulation
Regulates protein products
What are CpG islands
Cluster of C to G may be binding to epigenetics near the promoter region
Explain histone modification? What happens when you methylate and acetylate histones
Methylate = Off
Acetylate = On
Explain the levels of transcription you would likely see in heterochromatin and euchromatin
Heterochromatin: low and compact
Euchromatin: on and accessible
Mutation
Refers to the heritable change in genetic material
Silent Mutations
A mutation that does not alter the amino acid
CUU, CUC, CUA, CUG no matter what changes at the end, it will code the same amino acid and nothing changes or is detectable
Missense mutations
A base substitution that leads to a change in the amino acid sequence in the polypeptide, severe impact but i can either be very beneficial or very bad
If AAC is turned to AAA it is now a different amino acid
Ex. sickle cell
Nonsense mutation
A mutation that produces a stop codon
AUG| UAC > UAA so amino acid to stop codon
Ex. cystic fibrosis
Frameshift mutations
A mutation that involves an addition or deletion of nucleotide, which shifts the reading frame
AUG CAG UUU CAG
AUG CAG GUU UCA G…
Reverse mutation
A mutation that converts mutated allele to a normal allele
Transition
Purine can replace a purine or a pyrimidine replaces a purine
Purine: A switches with G
Pyrimidine: T switches with C
Transversion
Pyridine to Purine switching an A with a T
What is the difference between deleterious mutations, beneficial mutations and conditional
Deletion: bad
Beneficial: Positive
Conditional: Temperature
What is the common codon present in trinucleotide repeats?
CAG
What are the two features of trinucleotide repeat expansions disorders
1) Anticipation: condition worsens over several generations
2) Severity depends on who you inherit it from (X linked recessive is common in males)
What is the difference between depurination and deamination?
Depurination: removing the purine (A and G)
Deamination: Removing the pyridine (C and T)
What are examples of environmental factors that can cause mutations
UV Rays
X Ray’s
Gamma Rays
Proto-oncogene
Normal, non mutated gene with the potential to become an oncogene (cancer gene)
Metastatic
Cancer moves to a different site in the body (From arm to foot)
Malignant
Cancer that invades surrounding tissue (From breast tissue to surrounding tissue around it)
Epigenetics
Associated with some cancers by changing gene expression
Gene testing
Refers to the use of tests to discover if an individual has a genetic abnormality
Genetic Screening
Refers to a population wide genomic testing
How do tumor suppressors genes differ from oncogenes
STOP: Tumor suppressors gene inhibit cancer
P53 will stop cell division
GO: Oncogenes induce the growth
RAS regulated by GTP. When GTPase is low, it cannot remove GTP which means that GTP is constantly on therefore RAS is constantly on
IN observing human diseases, many genetic disorders exhibit a specific ________ meaning the disease tends to develop at a characteristic age
Age of onset
What is apoptosis and what are the mechanisms that facilitate it
Controlled cell death and causing inflammatory response
Capsases necessary for apoptsis allowing them to have controlled death
Autosomal
Dominant: Occurs in all sexes equally AA or Aa (50%)
Recessive: occurs in both sexes (25%)
Sex-Linked
Dominant: Lethal in XA XA or XA Xa
Occurs mostly in males: Xy
