Bio Unit 4

Differentiated Cell

When cells slowly over time change due to their fitness or mutations

mRNA

What molecule is the bridge between DNA and protein synthesis

Transcription

Synthesis of RNA

Where transcription occurs

• Eukaryotes - Nucleus

• Prokaryotes - Cytoplasm

RNA polymerase

Key enzyme in transcription

Role of Promoter

• Where the RNA polymerase binds to

• Unwinds strands of DNA

• Initiates the synthesis of mRNA at a start point

Transcription Factors

Proteins that control gene expression by binding to specific DNA sequences, repressing or activating it

Transcription Unit

Segment of DNA that is transcribed into an RNA molecule by the enzyme RNA polymerase

Terminator in Transcription

DNA sequence that signals the end of transcription

Role of RNA polymerase

Causes the synthesis of RNA

Initiation - Transcription

Unwinds the DNA and imitates the synthesis of mRNA at the start point

Elongation - Transcription

RNA polymerase builds complementary base pairs 5’ to 3’

Termination - Transcription

Stops it

TATA box

Binding site for RNA polymerase

Base Pair after transcription

ATCG → UAGC

Translation

Builds proteins from the mRNA

Where translation occurs

• Cytoplasm

• In eukaryotes, on the rough ER

RNA Splicing

• How mRNA transcript modified

• Introns are removed

• Exons are joined together

Introns

Non-coding regions

Exons

Coding regions

Central Dogma

The idea that DNA makes RNA and RNA makes proteins

Triplet Code

Genetic Code

Codon

The section of mRNA they use to make amino acids

Anticodon

3 nucleotides on the tRNA that corresponds to the mRNA so it can connect

Codon Start

• AUG

• Methionine

Wobble position of a codon

Third base of a codon can pair with the anticodon less exact than the first two

Attaches correct amino acids to tRNA

Function of aminoacyl-tRNA synthase

What ribosomes are made of

rRNA and ribosomal DNA

tRNA

What molecule binds to ribosomes

P Site

Holds tRNA carrying the growth polypeptide chain

A Site

Carries the tRNA with the next amino acid

E Site

Exit Site for the tRNA

Initiation - Translation

Site A is ready to accept tRNA for the first codon after AUG

Elongation - Translation

Goes through the PAE sites to create the amino acids

Termination - Translation

Stop codon reaches A site, causing dissociation of the ribosome from mRNA and tRNA

Free Ribosomes

Suspended in cytosol and synthesize proteins that remain in cytosol

Bound Ribosomes

• Attaches to cytosolic side of the ER

• Makes proteins

Point Mutation

• Chemical change in the genetic material of a cell or virus

• Occurs via random error or environmental factors

Silent Mutations

• No change in the amino acid result

• Occurs in a region where exact sequence is not essential for function

Missense mutation

Change in single nucleotide changes what it codes for

Nonsense Mutation

Premature stow codon

Insertion

Added nucleotide

Deletion

Deletes a nucleotide

Frameshift

Shifts where the codons are and changes everything after point of shift

Operon for E. coli

Repressible Operon

Operon

A unit made up of linked genes which is thought to regulate other genes responsible for protein synthesis

Promoter

Binding site for RNA polymerase, acts as an on switch for a gene

Repressor

A substance that acts on an operon to inhibit messenger RNA synthesis

Corepressor

Molecule that represses an expression of genes

Regulatory Gene

Regulates the gene

trp Opern

• On when tryptophan levels are low

• Off when tryptophan levels are abundant

Repressible Operon

trp Operon is a(n) ______

Inducible Operon

lac Operon is a(n) ______

Evolution

Change in allele frequencies of a population over time

Population

A group of the same species that inhabit the same geographic range at the same time

Origin of Species

• Written by Charles Darwin

• 1859

• Natural selection of evolution

Bogs

What environment provides the best fossils record 

Sedimentary Rocks

What type of rocks holds the most complete fossil records

Cuvier

• Paleontologist who believes in extinction, but not evolution

• Older fossils are different to modern forms

Lyell

• Species change to keep up with the Earth changing

• Influenced by Darwin

Lamarck

• First proposed evolution mechanism for how life changes over time

• Passed genes to children

• Wasn’t supported by evidence

Wallace

Natural selection similar to Darwin

Charles Darwin

• The Voyage of the Beagle

• Galapagos Islands

• Questions the creation story because the costal animals looked different from the land animals

5 Mechanisms of evolution

• Mutation

• Gene Flow

• Nonrandom Mating

• Natural Selection

• Genetic Drift

Mutation

Doesn’t affect it that much, more important in organisms that asexually reproduce

Gene flow

Movement of alleles from one population to another

Nonrandom mating

Form of natural selection that depends on individual’s ability to obtain a mate

Genetic Drift

Change in alleles due to random chance

Artificial Selection

Humans breeding things together to get a specific outcome

Bottleneck

• Genetic Drift

• A catastrophic event kills a good portion of the population and narrows the gene pool

  
  

Founder Effect

• Genetic Drift

• The portion of the population gets separated from the rest, gene pool is different

3 Factors for natural selection

• Variation

• Heritability

• Different reproductive success

3 Modes of Natural selection

• Directional

• Disruptive

• Stabilizing

Directional

Favors one extreme

Disruptive

Favors both extremes

Stabilizing

Favors the medium variation

Gene flow

The genes available in a population

Descent with Modification

How parents pass on their traits

Differential reproductive success

The difference in reproductive success among different organisms in a population based on their fitness

Homologous Structures

Structures between similar animals that match due to evolution

Vestigial Organs

Still around features that is no longer useful

Convergent Evolution

Independent evolution of similar traits

Analogous Structure

The structures that are the same between species that are not due to the same ancestor (Convergent Evolution)

Biogeography

Study of life geographically

Bioinformatics

Analyzing genetics (To possibly change it)

Macroevolution

Broad patterns of evolution changes above the species level

Speciation

Species evolving into two or more different species over time

Specie Definition

• Behavioral

• Temporal

• Mechanical

• Habitat/Ecological

• Gametic

• PostZygotic

Behavioral 

Not having the right song to mate

Temporal

Mates at different times/seasons

Mechanical

Sizes physically disallow reproduction

Habitat/Ecological

Distance/Location

Gametic

The sperm shape stops the egg from being fertilized across the different species

PostZygotic

Reduced Hybrid viability/fertility

Hybrid

Cross across species

Hybrid Inviability

Cannot survive past embryonic stage

Hybrid Sterility

Hybrid survives but cannot reproduce

Low Hybrid Viability 

Survives but has lower fitness and it less likely to reach maturity 

Allopatric Speciation

Geographically separated

Sympatric Speciation

Everything else; plant getting more than one sperm at once and increasing gene amount