MCDB 1A Lecture 2

Macromolecule 3: Proteins

-exhibit incredibly diverse biological functions

-do everything in the cell except for information storage

Enzymatic Proteins

-catalytic activity, speeding up chemical reactions

-example: digestive enzymes catalyze the hydrolysis of bonds in food molecules

Defensive Proteins

-help identify and protect diseases, like antibodies that bind to viruses

Storage Proteins

-storage of amino acids

-make it easy for developing embryos to have a ready support of amino acids

Transport Proteins

-transport of substances

-exist inside of the fluid mosaic cell membrane

-like hemoglobin in our red blood cells that bind oxygen and carbon dioxide, taking oxygen from the lungs to the tissues, and carbon dioxide from the tissues to the lungs

Hormonal Proteins

-coordinate the activities of an organism

-insulin is a protein that is created by the pancreas that causes other tissues to pick up glucose, which helps us regulate our blood, and blood sugar

Receptor Proteins

-respond to chemical stimuli, signaling molecules, especially in our nervous system

Contractile and Motor Proteins

-movement

-when they do their actions, they can contract and allow us to move an exert force on things

-can move things like cilia and flagella that can help amoebas and stuff move around

Structural Proteins

-support

-allow for fibrous frameworks and connective tissues, making sure they are sticking together really well

The monomers of proteins are called...

amino acids

4 Key Features of Amino Acids

-Amino group (directionality/bonding)

-Carboxyl group (directionality/bonding)

-R-group side chain (variety of amino acid)

-Alpha Carbon

Amino acid variety is owed their different to...

R-groups

What are the 3 broad categories of R-groups

-Nonpolar (hydrophobic groups)

-Polar (hydrophilic groups): attract polar molecules

-Charged groups: attract water and opposed ions

Bonds between amino acids are called...

peptide bonds

Peptide bonds are covalent bonds formed by...

a condensation/dehydration reaction

Peptide bonds link amino acids into...

larger polymers = polypeptides

Amino (left) end is called…

N-terminus

Carboxyl (right) end is called…

C-terminus

Primary, Secondary, and Tertiary structures happen on…

a single chain, a single polypeptide

Quaternary structures happen on…

multiple chains, polypeptides

Primary Structure

-amino acids are held together by peptide bonds

Secondary Structure

-hydrogen bonds

The two types of secondary structure motifs are…

-alpha helix

-beta pleated sheet

What atoms are responsible for the forming of hydrogen bonds?

Hydrogen and Oxygen

Tertiary Structures

-formed when secondary structures fold back onto themselves, largely based on ionic and covalent interactions between R-groups

Tertiary structures are driven by…

hydrophobic interactions, van der Waals forces

Tertiary structures are stabilized by…

disulfide bridges and ionic interactions

Quaternary Structure

-forms a functional protein compromised of two or more subunits

-assembled from multiple combined tertiary structures (folded chains)

What can cause a protein’s structure to denature"?

alterations in pH, salt concentration, temperature, or other environmental factors

Denature

loss of a protein’s native structure, unravelling

Macromolecule 4: Amino Acids

-storage, transmission/signaling, expression of genetic information, and catalytic functions

What are the monomers for nucleic acids?

nucleotides

Features of nucleic acids include…

highly charged, sugar-phosphate backbone, directionality, base-pair complementarity

The three components of nucleotides are…

pentose sugar (identifies it as DNA/RNA), nitrogenous base (like an R group), and phosphate groups (place for bonding)

The three important carbons on the pentose sugar are…

the 5’ carbon, the 3’ carbon, and the 1’ carbon

DNA Nitrogenous base complementary pairing is…

A to T and C to G

The bonding between nitrogenous bases is…

hydrogen bonding

Nucleotides are linked together by…

a phosphodiester linkage to build a polynucleotide

Where does the phosphate bind on the nucleotide when DNA synthesis is occuring?

on the 3’ carbon of the pentose sugar

Pyrimidines (Nitrogenous Base)

Cytosine, Uracil, Thymine

Purines (Nitrogenous Base)

Adenine and Guanine

The two types of pentose sugars that distinguish nucleic acid acid types are…

Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

RNA can…

be an enzyme, do the same jobs as proteins, DNA, lipids, and carbohydrates

RNA is typically…

single-stranded. Complementary regions allow for following.

Erwin Chargaff

isolated DNA from various organisms and noticed that DNA had certain regularities. The ratios of A and T and G and C are the same.

Rosalind Franklin

used an x-ray source to take a picture of crystallized DNA. Her observations suggested that DNA is double stranded and has a sugar-phosphate backbone on the outside.