bio exam 3 chapter 5

Amino acids are

The building blocks of proteins

Amino acids contain

An amino group, R group, carboxyl group, a carbon, H group

R groups are

Variable, gives each amino acid at unique structure, and chemical properties

Amino acids are classified based on

Hydrophobic, hydrophilic, special

Hydrophilic can be broken down into

Polar, basic, acidic

Peptide bonds join

Two adjacent amino acids

Peptide bonds are a

Dehydration synthesis reaction

Peptide bonds are shorter than

Other single bonds and limit rotation

Protein folding is ultimately determined by

1° sequence of amino acids, interactions among the R groups

What are the four levels of protein structure?

Primary, secondary, tertiary, quaternary

The primary 1° structure is

Stabilized by peptide bonds and is three letter abbreviations

The primary 1° structure is a sequence of

Amino acids from the amino end to the carboxyl end

Secondary 2° structures are

Stabilized by hydrogen bonds between each amino acid carboxyl end and the amino end

The secondary 2° structure, alpha helix is

Right handed helices

The secondary 2° structure beta sheet is

Pleated and parallel/anti-parallel

The tertiary 3° structure is

A functional protein form and stabilized by many bonds

Protein structure determines

Its function

The shape of the functional protein results in

Active sites on enzymes, R group interactions with other molecules/proteins in/out of the cell

1° sequence dictates

Protein folding

Protein denaturation

Proteins can denature and lose their structure and function

Protein chaperones

Can help protect against denaturation

Quaternary 4° structure

Consist of two identical polypeptide subunits, hemoglobin is made up of four sub units two a sub units and 2B sub units

What three types of RNA does transcription produce

mRNA, TRNA, RRNA

mRNA

Codon triplets is transcribed message on mRNA, messenger

tRNA

Transfer, amino acid attachment site is specific to anticodon

tRNA anticodon is blank

Complementary to mRNA codon

tRNA synthetases

Binds to one uncharged tRNA, attaches the amino acid

rRNA

Ribosome, large and small sub unit

RRNA contains a site to

Facilitate specific binding of mRNA and TRNA to produce proteins

What are the three functional sites of a ribosome in the large subunit?

A site, P site, E site

A site

Aminoacyl site, Accepts the charged tRNA and forms peptide bonds

P site

Peptidyl site, peptidyl transferase activity occurs

E site

Exit site, uncharged tRNA exits the ribosome

Reading frame for codon’s translation begins with

A start codon

Cellular components required for translation

mRNA, ribosome, tRNA, aminoacyl trna synthetases, initiation factors, elongation factors, release factors

Initiation phase of translation

Forming the initiation complex

Initiation factors recruit, the small ribosomal subunit and TRNA and scan the mRNA for an AUG codon

When the complex reaches an AUG the large ribosome sub unit joints and initiation factors are released

Elongation phase of translation

Forming peptide bonds

Peptide bond is formed when tRNA enters the a site

The ribosome moves down one codon which puts the TRNA carrying the polypeptide into the P site and the now uncharged tRNA into the E site where it is released a new tRNA complementary to the next codon binds to the a site

The polypeptide transfers to the amino acid on the tRNA in the a site the polypeptide is elongated by repeating steps, three and four

Codon chart is used to translate

mRNA into amino acids

Standard genetic code is

Redundant, has 64 codons, 20 amino acids, some amino acids have greater than one codon

Termination phase of translation

Encounter a stop codon

When the ribosome encounters a stop codon a protein release factor combines with the a site the binding triggers release of the polypeptide chain from the final TRNA and disassociated of the ribosome subunits

Translation in prokaryotes

Shine dalgarno sequence

The ribosome binds to any shine dalgarno sequence with translation beginning at the first downstream AUG start codon so one mRNA can code for several poly peptides

A functional protein needs to be blank into blank

Folded, specific conformations