Genetics, Cell Division, and Gene Expression Flashcards
What is a nucleotide made up of?
Pentose + Base + Phosphate(s)
How are carbons numbered in sugar in nucleotides?
The 1’ goes at the sugar connected to the carboxyl.
The Nitrogenous base is attached to the 1’ prime carbon
The Phosphate groups are attached to the 5’ carbon
What is a nucleoside?
Just the nitrogenous base and the sugar in a nucleotide
What are the purines
These nitrogenous bases have two rings
* Adenine (A)
* Guanine (G)
What are the Pyrimadines
These nitrogenous bases only have 1 ring
* Uracil (U)
* Cytonsine (C)
* Thymine (T)
“Reading” vs “Writing” directionality of DNA
3’ → 5’ (Reading)
5’→3’ (Writing)
How many H-bonds are there in an A-T bond?
How many in a C-G bond?
A-T: 2 H-bonds
C-G: 3 H-bonds
Is DNA symetrical on both sides?
DNA is twisted into a helix, but it is not symmetric
What do DAPI stains attach to in cells
The DAPI stain attaches to the minor groove of DNA
* It aslo stains organelle DNA (mitochondria and chloroplasts)
What are the different types of double stranded DNA?
A-DNA
Adaptation to desiccation?
B-DNA
Most common type by far
Z-DNA (left handed)
Implicated in disease?
Prokaryotic Chromosome
Circle of double-stranded DNA
* 0.5 – 7.0 Mb long
* Most bacteria have 1 copy per cell
* It contains all the genetic information needed to function and reproduce
* It is replicated during cell division
Prokaryotic Nucleoid
60% DNA (circular chromosome) + DNA-binding proteins not forming nucleosomes
* Arguably some RNA
* NO membrane!
This is the Prokaryotic equivilant of a chromosome
Prokaryotic Plasmids
- Usually small (but it can be quite large)
- Circular dsDNA
- No DNA-binding proteins
What are the different ways of storing DNA (in order of most availible to least availible)
- DNA
- “beads on a string”
- 30 nm fibre
- 120 chromonema
- 300-700 nm chromatid
- 1400 nm mitotic chromosome (supercoiled lineral DNA)
Note: organelle DNA stays circular
What are the states of active DNA
- DNA
- Beads on a string
Single-Strand Binding proteins
SSB proteins prevent annealing (coming back together) of the separated strands and protects the open strand from enzymatic attack
The “Central Dogma”
Information flows from DNA (to DNA) to RNA to proteins
Where does DNA stay? Where do ribosomes stay?
How does the DNA get to ribosomes?
DNA is (and stays) in the nucleus
Ribosomes are (and stay) in the cytosol
Conclusion: RNA shuttles information from the DNA in the nucleus to the ribosomes in the cytosol where proteins are made
What is a gene?
A portion of DNA that encodes a functional RNA
Can be protein-coding or non-protein-coding
Chromosome 1 examples:
* Gap junction protein conexin 31
* Collagen alpha 1
Messenger RNA (mRNA)
Messenger RNA is responsible for relaying the information stored in DNA
How many Nucleic Acids do we make?
DNA: only 4 bases
Protein: 20 residues (+2)
3 Bases = 1 Codon → 1 Amino Acid
Mutations
Are changes in the sequence of bases in the DNA
Are sometimes visible, other times not
Can be deleterious, neutral, or beneficial
Variants
Genetics
When a change does not affect function but rather strength of a phenotype is often called a variant
What are the types of genetic mutations
Framshift
* Deletions (single base or codon)
* Insertions(single base or codon)
Base Substitutions
Note: Many of the base substitutions are invisible mutations
Semi-Conservative Replication
When DNA duplicates, it keeps one strand and makes a new one
DNA replication Summary (Bacterial Model)
Separation
● Straightening → Topoisomerase
● “Unzipping” → Helicase
● Maintaining strands separated → Single-strand-binding proteins
Elongation
● RNA Priming (sometimes DNA) → Primase (a kind of polymerase)
● Synthesis → DNA Polymerase III
● Proofreading → DNA Polymerase III
● Replacing RNA with DNA → DNA Polymerase I
● “Stitching” DNA → DNA Ligase
Replication Fork
Genetics
Topoisomerase relaxes the double helix so it can be “unzipped” without the tensions created by the twist
Class I Topoisomerase
Cuts the sugar-phosphate backbone to allow for over-/under- winding, then repairs the bond once it’s done
Helicase
Pulls apart the double strand so each strand can be accessed individually
Which direction do you transcribe the template strand?
DNA
3’ to 5’ (reading)
Note, the nucleotides you’re adding are from the 5’ to 3’ direction
What needs to happen before DNA pol III can add nucleotides to a lone template strand?
Primase needs to create a primer of ~10 RNA NTs on the DNA template strand
DNA pol III can add dNTPs once a primer is in place
What is the function of primase?
Primase is a kind of RNA polymerase It adds RNA nucleotides:
● ATP
● UTP
● CTP
● GTP
onto a template strand
This must be done before DNA polymerase can add nucleotides to the template strand
What are the functions of DNA (or RNA) polymerase
Many different types exist they all:
● Add nucleotides 1 at a time
Most of them also:
● Perform proofreading
Some of them also:
● Remove primers
What structure proofreads errors during elongation
DNA pol has a proofreading function, if the wrong base is added, it removes it before continuing, then adds the correct base and continues with the extension
Which direction is DNA elongated
5’ to 3’
Leading vs Lagging Strand
DNA Replication
Leading strand follows the direction of DNA helicase.
The lagging strand elongates in the opposite direction of the DNA helicase.
Whats an Okazaki fragment
The little bits of code on the lagging strand
Note: not the primer
What is the function of DNA Ligase
Ligase joins broken DNA
Useful for joining Okazaki fragments during replication but also for repairing DNA that has been damaged by environmental factors such as radiation
Explain DNA Replication in the Bacterial Chromosome
The circular bacterial chromosome has a single origin of replication
From the OOR, two helicases begin to separate the strands in opposite directions, forming a replication bubble
Eventually the replication forks meet and the replication is complete
* Termination sequences and a special protein help to seperate the forks where they meet
Explain DNA Replicaton in the Eukaryotic Chromosome
The linear eukaryotic chromosome has a multiple origins of replication
From each OOR, two helicases begin to separate the strands in opposite directions, forming a replication bubble for every origin
In humans there are about 100000 OOR in total
What’s a Telomere? What does it do?
Telomeres are repetitive sequences (TTAGGG mammals)
The ends of eukaryotic chromosomes are capped by telomeres
DNA pol cannot copy to the very end of a strand so capping sequences provide a buffer to avoid information loss
Telomerase
Telomerase maintains the telomeres
The activity of the enzyme is reduced in adult cells and one of the theories of aging involves the shortening of the telomeres leading to health problems as cells divide
Note: too much tlomerase activity is linked to cancer
Explain DNA replication in Achaea
Circular chromosome but multiple origins of replication
What nitrogenous bases ten to be rich in origins of replication
Origin of replication sequences tend to be AT-rich
Polymerase Chain Reaction (PCR)
A laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA
Explain the significance of thermophilous bacteria
Thermophilous bacteria revolutionized molecular biology
As a thermophile, its enzymes are stable at high temperatures
The DNA pol used in PCR comes from T. aquaticus and is known as Taq pol
Transcription
The synthesis of RNA from DNA
RNA becomes a messenger carrying DNA instructions
RNA polymerase
Does everything:
● Separates DNA
(no helicase needed)
● Reads DNA and synthesises RNA
● Proofreads the growing RNA strand
Which direction is “upstream”
Upstream - Toward the 5’ direction
Downstream - Toward the 3’ direction
Antisense strand
Another word for template strand
RNA pol only reads this
Promoter
Genetics
● A region used to recognise the “beginning” of a gene during transcription
● Transcription factors and RNA pol bind to different sections of the promoter to begin transcription
● TATA box is a conserved sequence of most promoters and marks the specific section for RNA pol to bind to
TATA Box
Genetics
● The general TATA sequence is TATAWAW (W can be A or T)
● TATA-box binding protein binds to the TATA box sequence and crimps the DNA
● RNA pol binds downstream of this protein to begin transcription
Initiation
Genetics
The process assembling all the machinery needed for transcription to occur
The 35s Promoter
A gene alone is not enough to make a protein, the promoter has the function of telling RNA pol to make RNA from the gene
Regularly used to drive the expression of recombinant proteins in plants
Intrinsic Termination
The same transcript that is being produced signals the termination of the transcription
Operon
Genetics
● The operon is a gene structure that allows more than one gene to be controlled by the same operator
● Example: lac operon, the genes that control proteins related to lactose acquisition and metabolism
Was the process of transcription like in bacteria
Transcription coupled to translation
● No further processing of RNA is required
Was the process of transcription like in Eukaryotes
The transcribed RNA needs further processing in Eukaryotes
● In eukaryotes, transcription produces immature messenger RNA or ‘pre-mRNA’
● pre-mRNA processing is known as
post-transcriptional modification
5’ Capping
A modified guanosine is added at the 5’ end: 7-methylguanosine
3’ end trim
● 10 – 30 nt downstream of the sequence AAUAAA (or AUUAAA) the end of the capped pre-mRNA is cleaved (cut off)
● Many factors are involved
Polyadenylation
● A long tail of adenosines is added at the 3’ end (about 250-nt long)
● This is known as polyadenylation
● Poly-(A)-polymerase adds the ATP’s
Splicing
Genetics
● Introns are removed
● Messenger RNA (mRNA) is now mature
Major types of RNA
● mRNA — Messenger
● rRNA — Ribosomal
● tRNA — Transference
Whats the steps of processing rRNA
This is highly efficient: transcribe a single gene, obtain three separate components
rRNA makes up the ribosomes together with proteins
What are the steps in processing tRNA
tRNA is the RNA that transfers single amino acids to the ribosome during protein synthesis
Processing is necessary to force the tRNA into the proper shape to fit in the ribosome
Why do we modify bases?
Genetics
Modified bases let tRNA assume complex shapes not achievable with regular bases
Common modifications:
* Adenosine (A) → Inosine (I)
* Uridine (U) →Pseudorine (♆)
Tertiary Structure of tRNA
Complex 3D twists and turns give the tRNA a functional shape
True or false
Prokaryotes process mRNA
False
* Only Eukaryotes do this
Summarize mRNA processing
This is a multi-step process done to ensure the integrity of the mRNA
* This is also known as
* post-transcriptional
* modifications
* Fully-processed mRNA is also called mature mRNA
Steps:
* Capping
* Cleaving
* Polyadenylation
* Splicing
Alternative Splicing
Genetics
“Cutting out” different bits of the same genetic code to make different protiens
Translation
Genetics
The synthesis of protein from RNA (mRNA)
DNA: encrypted instructions
mRNA: unencrypted message
Protein: translated (effected) message
* Puts the intructions in the message into action
How to amino acids get onto the tRNA
Amino acids need to be “loaded” onto tRNA
Aminoacyl-tRNA synthetase binds the tRNA (catalytic site) and attaches the amino acid at the 3’ end (editing site)
Aminoacyl-tRNA synthetase
“Aminoacyl-tRNA synthetase” is any enzyme from a family of synthetases
* There is one for each tRNA-aa pair
Aminoacyl-tRNA synthetase binds the tRNA (catalytic site) and attaches the amino acid at the 3’ end (editing site)
What needs to be done to amino acids befor loading them
Genetics
Before loading, aa’s need to be “activated”
aa + ATP → aa-AMP + PPi
aa-AMP + tRNA → aa-tRNA + AMP
Wobble Pairing
Genetics
Some aa’s are encoded by multiple codons, but there is only one tRNA anticodon to match with each codon.
How? → The “wobble” position.
The “wobble” is made possible by modified bases
Inosine (I) can pair with C, U, and also A (recall than I is A modified)
Guanine (G) naturally pairs with U besides the normal C pairing
Shine-Dalgarno Sequence
Prokaryotes contain a highly-conserved recognition sequence where the small ribosomal subunit binds:
AGGAGG[U]
There can be multiple of these sequences
* Transcripts with multiple Shine-Dalgarno sequences also have multiple START and STOP codons
How does ricin (a poison work)
Ricin removes a single adenine from the sarcin/ricin loop in the ribosomal RNA, this inactivates the ribosome
How does the death cap mushroom affect the body
It inibits RNA pol II
Polypeptide = Protien?
NOPE
The polypeptide must be folded and have a purpose to be a protein
“Protein folding is the first, most obvious change that happens to a polypeptide chain after it has emerged from the ribosome”
How important is protein folding?
The only thing that makes a protein work is its shape!!!
Wrong shape = useless or
harmful
* Prions
* Alzheimers
Are prions infectious?
Prions: infectious disease-causing proteins
Prions force normal proteins into bad shapes
Chaperones
Genetics
Chaperones help proteins fold
They are proteins that protect other proteins from their surroundings so they can fold without interacting with other elements that could cause them to misfold
Hsp90
Genetics
Hsp90 maintains protein “health” for a number of specific proteins
Exactly what these protein does is not entirely clear but is helps to maintain proper folding during stress
* It works with ATP and Sba1, a co-chaperone protein
What are some common ways of modifying protiens?
Most proteins require changes before being functional
Cleaving - Protein function
Phosphorylation - General Activation
Acetylation - Gene Expression
Methylation - Protein Function
Cleaving
Protein Modification
Bits and pieces of the polypeptide may have to be cleaved for proper function
Example: pepsin and pepsinogen
* Pepsin is an enzyme that digests proteins
* Pepsinogen is the proenzyme and it is not active
* In low pH, pepsinogen cleaves itself and becomes pepsin
Protein Sorting
Proteins need to be localized to their target site within the cell
* Proteins have recogniseable sequences or “signals” used in trafficking
Target: cytoplasm → Free ribosomes simply release it in the cytoplasm
Target: cell compartment or
export → Ribosomes localise to the ER where polypeptides can be processed in the (ER’s) lumen
What is the signal recognition particle
Protein Sorting
The signal recognition particle is a ribonucleoprotein
* Note: this is on the protein sequence
Can some orgenelles make some of their own proteins?
Yes
Mitochondria and chloroplasts have their own ribosomes to make some proteins from their own mRNA transcribed from their own circular DNA
Example: RuBisCO’s large
subunit is synthesized by
chloroplasts’ ribosomes.
How are proteins localized to different places (in Eukaryotes)
Cytosol
No signal → free ribo. → no signal
Nucleus Mitochondria, Plastids, Peroxisomes
No signal → free ribo. → organelle signal
Export
ER signal → ribo. @ ER → no signal
Plasma membrane, Nuclear envelope, ER, Golgi, Lysosomes
ER signal → ribo. @ ER → organelle signal
How are proteins localized in prokaryotes
Localization happens by recognition of protein signal sequences
What is the product of gene expression for protien-coding genes
For protein-coding genes, the product of gene expression is the protein it encodes
Note: Expression needs to be highly regulated or else chaos ensues
How do prokaryotes regulate gene expression?
Prokaryotes mostly regulate at the transcription level
How much mRNA is made dictates how much product is available
How to Eukaryotes regulate gene expression
Eukaryotes regulate at every possible level and then some
Every step that can be used for regulation is used for regulation
Why?
* Many Eukaryotes are multicellular, so unregulated protein-synthesis creates problems
How do Eukaryotes cue transcription?
Eukaryotes use an enhancer region
Together with specific transcription factors (activators) they are part of the transcription initiation complex
All cells in your body have the same DNA. How come your skin cells and your liver cells show different genetic expression?
All cells share the same genes, but different genes are expressed in different cells
Multicellular Eukaryotes need to coordinate which cells express what
Together with specific transcription factors (activators) they are part of the transcription initiation complex
How does miRNA regulate translation
miRNAs interrupt the translation process by binding to the mRNA and impeding the ribosome
What influences the life of the transcriptome
5’ UTR’s imprint the half-life of the transcript
Poly-A tail length affects the half-life R
Ubiquitin
● Regulatory protein used by most Eukaryotes
● It’s called ubiquitin because it’s ubiquitous!
● It’s a small protein, just 76 aa-long in humans
Ubiquitin proteins tag other proteins.
At least 4 needed for degradation
Affects protein:
● Degradation
● Location
● Activity
● Interaction
Proteasome
Protein shredder
● Destroys proteins
● Active sites are on the inside to protect the cell
● The ends are capped
● Shreds proteins into 3 – 23 aa-long pieces
True or False
Epigenetics are changes to the DNA code
Epigenetics are changes to the DNA molecule, but not to the code!
* Histone tails can be acetylated, DNA can be methylated
* DNA methylation is said to “tag” the DNA in specific ways
Chromatin remodeling
Semipermanent and heritable.
Large implications such as in addiction models and other social issues such as trans-generational trauma.
X chromosome inactivation
Some female mammals (including humans) randomly inactivate one copy of their X chromosome
Example: the coat pattern of a calico cat
Do mutations need to occur in the protein-coding region to have an effect?
NOPE
Mutations need not occur in the protein-coding region to have an effect
Example: Haemophilia
Several possible mutations. Most common forms involve a mutation to the promoter of a gene coding for a clotting factor.
Single-nucleotide polymorphism (SNP, pronounced ‘snip’)
A variant in the code of at least 1% of the population
Example: sickle-cell anemia
* Single-base substitution missense mutation in the 6th codon of the gene coding for haemoglobin
* Non-conservative
* mutation (aa’s with different properties)
Can Sickle-Cell Anemia be Advantageous?
Yes
Sickle-cell: a recessive evolutionary advantage
~4 million are homozygous
~43 million are “sickle trait”
Heterozygous “sickle-trait” individuals have resistance to malaria
* 80% of cases occur in Sub-Saharan Africa
Can silent mutations have an effect?
Yes
True or False
All genetic disorders are mutations
False
Examples:
* Turner syndrome (missing X chromosome)
* Cri du chat (missing part of chromosome 5)
* Down syndrome (extra chromosome 21)
What are some conditions started by SNPs
- Sickle-Cell Anemia
- Cystic Fibrosis
Sumarize the prokaryotic cell cycle
● B period: cell growth
● C period: DNA
replication
● D period: fission
THIS IS NOT MITOSIS!!!!
This is also exponential growth (in theory)
What is the name for Prokaryotic Cell Division
Binary Fission
ParABS system
The ParABS system ensures that the chromosome is segregated, the full mechanism is under investigation
Proteins parA and parB move the chromosome, without polymerising into long chains
* Not cytoskelital involvement
Prokaryote Exclusive!
What is parS, where is it Located?
ParABS system
ParS is a well conserved region of DNA
* It does not make a product, but s very useful in Prokaryotic DNA replication
It is located next to the origin of replication, making it the first to be replicated in DNA replication
What does ParB bind to? What does it do from there?
ParABS system
It binds to ParS
parB proteins are guided to move toward the opposite pole guided by a concentration gradient of parA proteins
How come both origins of replication don’t follow the ParA protien gradient?
ori #1 is anchored at the membrane at one of the cell’s poles
* This makes it so only ori # 2 can follow the gradient
ori #2 is anchored at the other pole once it gets there
Endospore Formation
This is a process that only occurs for some bacteria
* Only occurs when environmental conditions get hard
● Fission starts but stops at cell expansion
● A double-membrane capsule is formed around one chromosome
● The rest of the cell dissolves
This forms an endospore that can wait it out until conditions improve
What does the endospore structure constist of?
Includes:
● Double membrane
● One chromosome
● A few copies of DNA pol
● A few ribosomes
Excludes:
● Water (mostly)
Summarize the Eukaryotic cell cycle
G1: growth and RNA synthesis, no DNA synthesis
S: Synthesis of DNA proteins and DNA replication
G2: further growth and synthesis of mitosis-related RNA and proteins
M: Mitosis
Can cells exit the cell cycle?
Yes
* They can enter the G0 state, which stops them from starting DNA replication
Permanently: neurons
Temporarily: liver cells
In many tissues contact inhibition is a major trigger to enter the G0 state (cells can sense their neighbours)
What are the different rates of cell division
Some cells reproduce continuously, e.g.:
● Epithelial cells replace themselves
● Bone marrow is highly active
Some cells reproduce if required, e.g.:
● White blood cells
● Hepatocytes (liver cells)
Some cells cannot / will not, reproduce, e.g.:
● Neurons
● Red blood cells
What are the distinct phases of mitosis
Prophase: condensation
Prometaphase: spindle formation
Metaphase: chromosome alignment
Anaphase: separation of chromatids
Telophase: unpacking
G1: growth
Cell division
Cell synthesises proteins and ribosomes, and reproduces organelles in preparation for cell division
Assembly and loading of cohesin proteins
S: replication
DNA replication
Replication creates two chromatids from each chromosome
Cohesins are trimeric proteins that hold sister chromatids together
All of this happens in the nucleus
Centrosomes
The centrosome (a pair of centrioles) is replicated during the S phase, along with DNA (but in the cytoplasm)
Animal Only!!
G2: further growth and synthesis of all mitosis-related machinery
DNA is already duplicated, awaiting further cell preparations before division
Mitotic chromosomes are inaccessible, so all the components needed to carry out mitosis need to be synthesised before the DNA is fully condensed
What do condensin protiens do?
Condensin proteins contribute to chromatid condensation
* Cable Managment
* Keeps the chromasomes condensed
Karyotype
Diploid organisms have pair of homologous chromosomes
● Humans: 23 pairs
● Jack jumper ants:
○ Females: 1 pair
○ Males: 1 single (haploid)
● Ophioglossum pycnostichum:
630 pairs!!! ← a fern
how are sister chromatids anchored at one point
Condensed sister chromatids remain attached at one point by the centromere
A complex of proteins bind to specific regions in each chromosome, holding both chromatids
Centromere placement varies in each chromosome
Prometaphase
Spindle formation and nuclear dissolution
The spindle forms the tracks on which the chromosomes ride
Between prophase and metaphase, the spindle forms from the centrioles
It’s called a spindle for its shape, reminiscent of a drop spindle used for spinning yarn
What’s the spindle made of?
What do kinetochore proteins do
Kinetochore proteins are attached to the centromere
* Attaches chormasomes to the microtubule of the spindle
They link the mitotic chromosomes to the spindle
What happens during metaphase
Chormosome alignment
What happens during anaphase
Seperation on chromatids and elongation of the cell
How does cytokinesis work in animal cells
In animal cells, microfilaments divide the cell
They create a furrow by forming a ring around the equator and contracting it, like a drawstring
Differences in mitosis in plant cells (as opposed to animal cells)
Difference #1:
Cells expand during interphase, never during anaphase
* Plant cell walls need to loosen up to allow expansion
* Plants need to deal with the very specific process of cell expansion before or after attempting mitosis (but not during)
Difference #2:
No centrosomes
* But they do still have a mitotic spindle!
Difference #3:
No furrow in cytokinesis
* A phragmoplast forms a scaffold and vesicles deposit new cell wall
What are the major checkpoints of cell division
G1 — End of G1
Regulatory Protein: G1-CDK
G2 — Start of mitosis (G2/M)
Regulatory Protein: M-CDK
M — Start of anaphase
Regulatory Protein: APC
Regulatory proteins give the “go ahead” at each checkpoint
The cell cycle can be halted at any of these points
G1 Checkpoint
Controls the entry into the
S phase
This is the “commit to
division” checkpoint
Unicellular: is the cell large enough to reproduce?
Multicellular: is the cell supposed to reproduce?
* Neuron?
* Too close to other cells?
If all checks out:
● Activate G1-CDK
Otherwise:
● Remain in G0
G2 Checkpoint
Controls the entry into mitosis
Is DNA replication and repair
complete?
→ If no, wait
→ If yes, form the M-CDK complex (different cyclin and different CDK from G1)
M-CDK phosphorylates proteins involved with chromosome condensation
M Checkpoint
**Controls entry into anaphase **
Is every chromosome
attached to kinetochore MTs? → If no, wait
→ If yes, activate APC proteins
APC: anaphase-promoting complex; signals other proteins to break down cohesins
Mammalian growth factors
Growth factors regulate cyclin-CDK complexes
Can be:
● Positive (Platelet-Derived
Growth Factor)
* Promotes cell division
● Negative (Myostatin)
* Inhibits cell division
Minssense Mutation
A single nucleotide base in a DNA sequence is swapped for another one, resulting in a different codon and, therefore, a different amino acid
Nonsense Mutation
A mutation that changes an amino acid in a protein to a stop codon which ends synthesis of the protein at that location.
What is the start codon
AUG
What are the stop codons
Name all three
UAA
UAG
UGA
How are chromosomes moved during anaphase?
Kinetochores (motor protiens) rachet along the the microtubules, dissassembleing them in the process
How is cytokenisis different in plants from animals
No furrow in cytokinesis
A phragmoplast forms a scaffold and vesicles deposit new cell wall
In the ribosome, where does the tRNA first get loaded? Where does it exit?
Loading - A site
Creating amino acid - P site
Exiting - E site
What is the role of aminoacyl transferase in translation
It attaches the right amino acid onto the right RNA sequence
Which direction does DNA replicate
5’ to 3’
Note: this is the DNA be added or the “writting” direction
What are the steps of processing mRNA?
Why does mRNA need to be processed?
- Capping
- Cleaving
- Polyadenylation
- Splicing
This is done to ensure the integrity of the mRNA
* make sure the enzymes don’t eat it
True or false
Proteins mark important places on the pre-mRNA in all cells
False
This only happens in Eukaryotes
* They are things like splicing factors and cleavage factors
What is the name of the DNA region where the Pol begins?
The promoter
* The TATA box provides the specific section for RNA pol to bind to
What is the name of the DNA region where the Pol finishes
The terminator
* May be intrinsic (ex. terminating hairpin) or factor dependant (ex. Rho factor)
Variant
Genetics
When a change does not affect function but rather strength of a phenotype is often called a variant
