PROTEINS

Proteins

_____ are the most abundant organic molecules in the living system.

proteos

Greek word ____ meaning holding the first place.

nitrogenous organic compounds

These are _______ have large molecules weight of one or more long chains of amino acids.

20

Proteins are made from ____ a-amino acids. (chains of amino acids)

monomer

A single unit of amino acid is known as a ______ when many monomers combine together they form polymers.

hydrolysis

On ________, proteins give amino acids

Protein

They are involved in most of the body’s functions and life processes.

amino acid

Proteins are macromolecules – polymers of ____monomers, which contain both an amino and a carboxyl group

Structural proteins

Protein: _____

Function: Support

Enzymatic proteins

Protein: _____

Function: Increase the rate of biological reactions

Membrane transport proteins

Protein: _____

Function: Speed up movement of substances across biological membranes

Motile proteins

Protein: _____

Function: Produce cellular movements

Regulatory proteins

Protein: _____

Function: Promote or inhibit the activity of other cellular molecules

Receptor proteins

Protein: _____

Function: Bind molecules at cell surface or within cell; some trigger internal cellular responses

Hormones

Protein: _____

Function: Carry regulatory signals between cells

Antibodies

Protein: _____

Function: Defend against invading molecules and organisms

Storage proteins

Protein: _____

Function: Hold amino acids and other substances in stored form

Venoms and toxins

Protein: _____

Function: Interfere with competing organisms

Microtubule and microfilament proteins

______ and ______ form supporting fibers inside cells; collagen and other proteins surround

DNA polymerase

Among thousands of examples, ______ increases the rate of duplication of DNA molecules;

carboxylase/oxygenase

RuBP (ribulose], 5-bisphosphate) ______ increases the rates of the first synthetic reactions of photosynthesis

lipases and proteases

_____ in the digestive enzymes increase the rate of breakdown of fats and proteins, respectively

Ion transporters

_____ move ions such as Na, K+, and Ca2+ across membranes

glucose transporters

_____ move glucose into cells

aquaporins

_____ allow water molecules to move across membranes

Myosin

_____ acts on microfilaments to produce muscle movements

dynein

______ acts on microtubules to produce the whipping movements of sperm tails, flagella, and cilia (the last two are whiplike appendages on the surfaces of many eukaryotic cells)

kinesin

_____ acts on microtubules of the cyto skeleton (the scaffolding of eukaryotic cells responsible for cellular movement, cell division, and the organization of organelles).

Nuclear regulatory proteins

______ turn genes on or off to control the activity of DNA

protein kinases

______ add phosphate groups to other proteins to modify their activity

hormone receptors

_____ bind hormones at the cell surface or within cells and trigger cellular responses

cellular adhesion molecules

_____ help hold cells together by binding molecules on other cells

LDL receptors

_____ bind cholsterol-containing particles at cell surfaces

insulin

____ regulates sugar levels in the bloodstream

growth hormone

____ regulates cellular growth arid division

antibodies

_____ recognize, bind, and help eliminate essentially any protein of infecting bacteria and viruses, and many other types of molecule, both natural and artificial

ovalbumin

_____ is a storage protein of eggs

apolipoproteins

_____ hold cholesterol in stored form for transport through the bloodstream

ricin

____ is a castor-bean protein that stops protein synthesis

bungarotoxin

____ is a snake venom that causes muscle paralysis

C, H, O, N

Proteins are primarily composed of the chemical elements:

top

The -COOH group is put at the ____ of the projection formula

bottom

The R group at the _____ of projection formula

horizontal

The -NH2 group is in a ____ position of projection formula

levorotatory

the projection formula of proteins is always ______

Bronsted–Lowry principle

what principle is zwitterion

amino group (-NH₂); carboxyl group (-COOH)

Amino acids contain both an ____ and a _____

carboxyl

donating a proton from the ____ group

amino

accepting a proton at the ____ group

glycine

most amino acids are chiral except ____

isoelectric point

The _______ is the pH at which an amino acid has no net electric charge, meaning the number of positive charges equals the number of negative charges.

Cystein

______ is the only standard amino acid that has a side chain that contains a sulfhydryl group

dehydration synthesis

A peptide bond is formed by a ______ reaction between the NH2 group of one amino acid and the COOH group of another amino acid

Peptide Hormones

_______ are short chains of amino acids that act as chemical messenger in the body

• Oxytocin

• Vasopressin

The two best-known small peptide hormones from the pituitary gland

Oxytocin

stimulates uterine contractions during childbirth

Vasopressin (ADH)

regulates water balance in the body

Vasopressin (ADH)

Contributes to blood pressure regulation by constricting blood vessels

Enkephalins

____ are pentapeptides (5 amino acids long) produces naturally by the brain

Enkephalins

Functions as neurotransmitters involved in pain regulation

Enkephalins

They bind to specific receptor sites in the brain to reduce pain perception

Morphine and Codeine

____ mimic enkephalins by binding to the same receptors

• Glutamic acid (Glu)

• Cysteine (Cys)

• Glycine (Gly)

Glutathione is a tripeptide composed of:

Glutathione

Function as an antioxidant. Acts as a regulator of redox (oxidation-reduction) reactions inside cells