Midterm 1 Flashcards
Cell division
The process by which cells divide to make more cells
occurs for growth, healing, and reproduction
occurs by mitosis or meiosis 
Difference between prokaryotes and eukaryotes mitosis
Prokaryotes : genome is small and circular
Dna in cytoplasm
Eukaryotes
Genome is large and linear
Dna in nucleus
Cell cycle
G1 phase (gap 1 phase)
S phase (synthesis)
G2 phase (gap 2 phase)
M phase (mitosis)
G1 phase
Cell growth and cellular metabolism
S phase
Synthesis
Dna replication occurs here
G2 phase
Preparation for mitosis
Interphase
Time between successive mitosis’s
Comprised of G1, S and G2 phase
Quiescent
Cells that are not actively cycling that exit the cell cycle from G1 to G0
Ex. A neuron with its axons and dendrites would be quiescent
Forward mutation
Wild type to mutant type
Reverse mutation
Mutant type to wild type
Missence mutation
Amino acid to different amino acid
Nonsense mutations
Amino acid to stop codon
Silent mutation
Codon to synonymous codon
Neutral mutation
No change in function
Base substitutions
Changes one base for another
can be Transition and transversion
Frameshift mutations
Insertion and deletion
Expanding nucleotide repeats
Increase in the number of copies of a set of nucleotides
Purines
Adenine and Guanine
(Have 2 rings)
Pyrimidines
Cytosine Urasil and Thiamine
Have one ring
How many hydrogen bonds between A and T or A and U
2 hydrogen bonds
How many bonds between C and G
3 hydrogen bonds
What percent of dna actually codes for protein
5%
Template strand
The transcribed strand of DNA
Contains the transcription unit (a promoter, an rna coding sequence and a terminator)
Read 3’ to 5’
How does transcription begin
Promoter region of dna signals rna where to begin (transcription begins directly after it but not on it so it is not transcribed in rna)
It is located upstream
Terminator (transcription)
A sequence that signals where transcription is to end
Incorporated into RNA
Located downstream
In which direction is RNA synthesized?
5’ to 3’
Can genes be located in the + or - strand on DNA
Yes
Where is -10 located on dna
Upstream within the promoter as is the -35
Which enzyme is responsible for synthesizing RNA
Rna polymerase I for mRNA and II for other RNAs and III for tRNS
Where does dna enter rna polymerase 2
The cleft it enters with the template strand in the direction of 3’ first
What regulates transcription
The promoter/Operon combo
Negative regulatory proteins
Inhibit transcription
Positive regulator proteins
Activate transcription
Negative Inducible operons
When transcription of operon is usually off and something happens to turn it on
Regulator protein is a repressor that blocks binding of rna polymerase to promoter
Repressor needs to be relieved of its duties in order for transcription to proceed
Repressible operons
Operons that are normally on but something happens that turns them off
An inducer
Allows transcription to take place
A small molecule that binds to the inhibitor/repressor and inactivates it so repressor can no longer. Bind to dna
Lac operon
Negative inducible operon
Inhibitor regulator
Allolactose is the ligand that deactivates the inhibitor/repressor
Which genes does lac operon thing have
Lac z, lac y and lac A
Repressor protein of lac operon
Lacl
By how many times is the rate of synthesis of lac operon increased in the presence of lactose
1000
In 2-3 min
Components of translation
mRNA
Initiation factors
Elongation factors
Release factors
Aminoacyl tRNA synthases
tRNA
rRNA and ribosomal proteins
Non-overlapping genetic code
Each nucleotide is part of one codon
Degenerate genetic code
Most amino acids are specified by more than one codon
The genetic code is nearly universal
With minor exceptions each triplet/codon has the same meaning in all organisms
Adjacent codons
There are no spaces between them
Three steps in translation
Initiation
Elongation
Termination
Initiation
The initiator AUG codon is recognized and MET is established as the first amino acid in the new polypeptide chain
Elongation
Successive amino acids are added one by one to the growing chain
Termination
A stop codon is recognized by a release factor that mimics a tRNA resulting in the completed polypeptide chain being released from the ribosome
Bond between amino acids
Peptide bond
How many codons are there
64
Stop codons
UAG
UAA
UGA
Mendelssohn principle of segregation
In heterozygotes, alleles R and r segregate independently from one another
Mendels principle of independent assortment
Alleles on different chromosomes assort independently
Occurs during anaphase 1 of meiosis and anaphase of mitosis
You got this
I know
Dominant negative mutations
Loss of function that interferes with normal function
Dominant allele mutations
loss of function (ex no antenna) or gain of function
Incomplete dominance
Red+white = pink
Co dominance
Black + white = checkered
Ex AB blood
Penetrance
Percentage of individuals having the expected phenotype for their genotype
Either have it or don’t
Expressivity
The degree to which a character is expressed
5 properties of the genetic code
- There are no spaces between codons
- The genetic code is non-overlapping
- Most amino acids are specified by more than one codon
- The genetic code is nearly universal (each triplet codon has the same meaning in all organisms)
What bond holds the nucleotides together in dna
Phosphodiester bond between the oxygen at the 3’ end of DNA and the phosphate at the 5’ end of dna 🧬
Difference between dna and rna at 5’ end
And their size
Dna has a mono phosphate at 5’ end and rna has a triphosphate at 5’ end
Dna is very large whereas rna is small
How wide is dna
How wide is a chromatid
Dna is 2nm
Chromatid is 1400nm
Transition
Purine to purine (A to G)
Or pyrimidine to pyrimidine (T to C)
Transversions
Purine to pyrimidine (A to T, A to C, G to C, G to T)
Pyrinidine to purine (T to A, blah blah
Conserved substitution mutation vs non conserved
Both cases are missence mutations however in conserved mutations the new amino acid has similar chemical properties to original
In non conserved the new amino acid has different chemical properties than original
Hypomorph
Not wild type but not null allele either
Genotype that is not the wild type, but a mutant that has partial loss of function.
Roan
The codominant patterning on a cow
Penetrance calculation
Total number of individuals with phenotype(on pedigree ones that are coloured in)/ total number of individuals with genotype (on pedigree ones that are coloured or have a hat)
Theee possible causes of Penetrance and variable expressivity
- Environmental
- Epigenetic (changes in gene expression but not due to mutations)
- Maternal age (ex. The older the mother the milder the phenotype)