Unit 3 Macromoleculues Part 2: Proteins and nucleic acids

What is one of the most abundant org molecules and the most diverse?

Proteins!

What are enzymes?

Living cells produce these to be catalysts in biochemical rxns like digression

Hormones

Chemical signaling molecules, usually small proteins or steroids

What is denaturation

Loss of function due to changes in temp, pH, or exposure to chemicals

What are amino acids?

Monomers that comprise proteins

What is the general makeup of an amino acid

• all have a central C atom (called the alpha C)

• They are bonded to an amino group (NH2)

• They are bonded to a carboxyl group (-COOH)

• They are bonded to an H atom

What is a peptide bond?

A covalent bond that attaches to each amino acid by which a dehydration rxn occurs

• One amino acid’s carboxyl group and the incoming amino acid’s amino group combine, releasing a water molecule

What does aliphatic mean?

Org compounds in which C atoms form open chains not rings

Aromatic rings

Substances with certain rings in their side chains

• critical for protein structure stabilization

What is the primary structure of a protein

The amino acid’s unique sequence in a polypeptide chain

• gene encoding protein determines this unique sequence

Describe the secondary structure of a protein, what are the two types

Determined by local folding of a polypeptide

There is a-helix and B-pleated sheet

What is a-helix secondary structure of a protein?

• 3-6 amino acids reside in each turn

• R groups protrude

What is the B-pleated sheet organization of the secondary structure?

• H bonding between atoms on polypeptide chain’s backbone form “pleats”

• R groups attach to Carbon and extend above and below the pleat’s folds

Describe the tertiary structure of a protein, where do hydrophobic R groups lie in protein folding and where do hydrophilic R groups lie?

The polypeptide’s unique 3-D structure. Due to chemical reactions at work on the polypeptide chain

• The nature of the R groups in the amino acids involved can counteract forming the H bonds standard for secondary structure

• In protein folding the hydrophilic R groups lie on the outside and the hydrophobic R groups lie in the interior

Describe the Quaternary Structure of a protein

Formed in some proteins from several polypeptides, or subunits interacting with each other.

• weak interactions between the subunits help to stabilize the overall structure

Is denaturation ever reversible why or why not?

It is often reversible because polypeptide’s primary structure is conserved in the process if the denaturing agent is removed, allowing protein to resume normal functioning

• some are irreversible though

What are chaperones and how do they assist the protein in the folding process?

They assist the protein in the folding process by associating with the target protein during the folding process

• they prevent polypeptide aggregations that comprise the complete protein structure & disassociate from the protein once the target is folded.

Where is DNA found in eukaryotes vs in prokaryotes

• found in the nucleus of eukaryotes

• in prokaryotes DNA is not enclosed in a membranous envelope

What is chromatin?

In eukaryotic cells DNA forms a complex with histone proteins, forming chromatin

• chromatin makes up chromosomes

What is RNA and what does it do

Ribonucleic acid, is mostly involved in protein synthesis

What is a monomer of nucleic acid called? And what is the basic structure.

Nucleotide = monomer

• consist of a sugar, nitrogenous base, and phosphate

How is a nucleotide of DNA different from a nucleotide of RNA

They differ by a single hydroxyl group, with RNA have the group

What type of bond holds a polymer of nucleic acids together and what is important about this bond?

• Phosphodiester bond

• Formed by dehydration synthesis and forms this phosphodiester bond between 5’ carbon on one sugar and 3’ carbon on another

• Strong covalent bond

• Gives nucleic acids polarity

• Directs building of polymers- can only add nucleotides to 3’ end

What are the different nitrogenous bases?

Pyrimidines:

• single C-N ring

• Cytosine, thymine, and uracil

Purines:

• Two C-N rings

• Adenine and guanine

Which bases pair together and what tupe of bonds do they form with one another?

The bases pair together with H-bonds from one strand to another, important because we need to pull apart some sections of DNA; transcription, translation, replication

• If we had covalent bonds between these it would take too much energy to pull apart

Why are the base pairs and bonds between two strands of DNA important?

Purines pair with pyrimidines

• this is because of parallel stands, they want nice sizing

• double rings with single rings keep it physically from not having bend/kinks in the DNA

Describe the structure of the DNA polymer vs the RNA

DNA:

• double helix

• Sugar-phosphate backbone

• Nitrogenous baes are on the inside

• Held together by H bonds

RNA:

• single stranded

• forms loops, hairpins, bulges

• folds into 3-D shape

Function of dna vs rna

DNA: Carries genetic info

RNA: protein synthesis along with many others

Two categories of RNA are what?

Coding and non-coding

What is the main coding RNA? And its function?

mRNA= messenger RNA

carries “message” from DNA to cytoplasm

What are the main non-coding RNAs?

rRNA= ribosomal RNA

• where the message is translated into polypeptide chain

tRNA= transfer RNA, link between mRNA and growing amino acid chain

What are the function of microRNAs?

Smallest RNA and they regulate gene expression by interfering w/t expression of some mRNA messages

Describe the process of transcription vs translation in brief

Transcription: Process in which DNA dictates the structure of mRNA

Translation: Process which RNA dictates the protein’s structure