vce biology 3/4

amino acids

monomers of proteins

amine group

NH2 part of amino acids

variable R group

it differs between the 20 amino acids and gives each one its properties

condensation polymerisation

a reaction that joins 2 monomers to make a larger molecules

peptide bond

form between amino acids and also create water

polymer

something made of repeating subunits (monomers)

primary structure

sequence of amino acids in the polypeptide chain

secondary structure

formation of alpha helices, beta pleated sheets or random coils

bonds in secondary structure

Hydrogen bonds between adjacent amino acids

random coils

A section of a polypeptide chain that is neither an alpha helix nor a beta-pleated sheet. Denatured proteins are reduced to random coils.

tertiary structure

formation of a complex 3d structure of a protein

quaternary structure

2 or more polypeptide chains join

prosthetic group

non-protein of organic factor that are essential for protein function

protein secretory pathway

ribosome, rough er, transport vesicle, Golgi body, secretory vesicle, cell membrane

ribosomes

site of polypeptide synthesis. contains a large and a small subunit made up of rRNA and protein. not membrane bound

free ribosome

a ribosome in the cytosol every polypeptide begins here and proteins for use inside the cell are finished here

bound ribosome

a ribosome attached to the rough ER makes polypeptides that carry a signal sequence for export

signal sequence

a short chain of amino acids at the start of a polypeptide that directs its ribosome to the rough ER. part of the polypeptide

rough endoplasmic reticulum

network of membranes with ribosomes attached. polypeptides for export enter its lumen and fold here

lumen

the space inside the membranes of the rough ER or the golgi apparatus

glycoproteins

a protein with carbohydrate attached. carbohydrate is first added in the rough ER and more is added in the golgi apparatus

lipoprotein

A protein with lipid attached

cytoskeleton

A network of protein fibres in the cytosol. Vesicles travel along it, and this movement uses ATP.

transport vesicle

form by budding of the RER and proteins are packaged for protection

Golgi body

stack of flattened membrane sacs that modifies, sorts and packages proteins.

cis face

The receiving face of the Golgi apparatus. It faces the rough ER, and transport vesicles fuse with it.

trans face

The shipping face of the Golgi apparatus. It faces the plasma membrane, and secretory vesicles bud off from it.

secretory vesicle

A vesicle that carries the finished protein from the trans face of the Golgi apparatus to the plasma membrane.

nucleotide

nucleic acid monomer

deoxyribonucleotide

monomer of DNA

ribonucleotide

monomer of RNA

phosphate group

PO₄^3-

pentose sugar

5 carbon sugar and central to a nucleotide

adenine

purine nitrogenous base, pairs with thymine in dna and uracil in rna

thymine

pyrimidine nitrogenous base pairs with adenine in dna and replaces by uracil in rna

guanine

purine nitrogenous base pairs with cytosine in both dna and rna

cytosine

pyrimidine nitrogenous base pairs with guanine in both DNA and rna

uracil

pyrimidine nitrogenous base that pairs with adenine in rna and does not exist in dna

exons

stay in mRNA and regions of DNA that have information to make proteins

promoter

front of the sequence the location where the enzyme RNA polymerase binds and initiates the beginning of gene expression

gene expression

the process of reading the information stored within a gene to create a functional product (usually proteins)

introns

removed via RNA splicing during gene expression. Regions of DNA that do not hold info for protein synthesis

terminator

end of gene and when rna polymerase reaches here it detaches

prokaryotic gene expression

no introns

operator

repressor proteins bind here to regulate gene expression

terminator

rna polymerase reaches and detaches here

operon

related functions are grouped together and controlled by one promoter cluster of genes located and transcribed together.

nucleus

organelle with a double membrane that contains the cell’s dna

gene

a section of dna that contains information for the synthesis of one protein

nuclear envelope

the double membrane that surrounds the nucleus the rough er is joint to this

nuclear pore

an opening in the nuclear envelope that lets large molecules move in and out of the nucleus

nucleolus

a region inside the nucleus that makes ribosomal subunits

exocytosis

the release of material from a cell when a vesicle fuses with the plasma membrane. form of bulk, active transport and requires atp

bulk transport

movement of large amount of material across the plasma membrane inside vesicles

atp

The molecule that supplies energy for vesicle movement and exocytosis.

mitochondria

Organelles where aerobic cellular respiration makes most of the cell's ATP. They supply energy but are not a step in the route of the protein.

endomembrane system

The connected membranes of the nuclear envelope, rough ER, Golgi apparatus, vesicles and plasma membrane. Membrane moves between them as vesicles.

parts of a nucleotide

phosphate group, pentose sugar, nitrogenous base

5’ end

free phosphate group

3’ group

a free OH-

mRNA

carries a copy of a gene’s instructions to a ribosome

tRNA

brings amino acids to the ribosome

rRNA

combines with proteins to form ribosomes

restriction enzyme cuts

phosphodiester bonds in the sugar phosphate backbone

RNA

usually single stranded, made of nucleotide monomers with ribose and the bases of A, C, G, U

number of amino acids

20

essential amino acids

cannot be made by the body so it must come from diet (9)

non essential amino acids

can be made by the body (11)

phosphodiester bonds

the strong bond joining the sugar (3” carbon) of one nucleotide to the phosphate of the next

antiparallel

2 dna strands that run in the opposite direction

denaturation of dna

separating the 2 strands of DNA by breaking the H bonds, usually with heat

mitochondrial dna

small circular dna molecule found inside mitochondria, not wrapped around histones

chloroplast dna

small circular dna molecule found inside chloroplasts in plant cells, not wrapped around histones

dna in a typical bacterial cell

usually one circular chromosome that sits in the cytoplasm, no nucleus and the dna is no organised into eukaryotic nucleosomes

carboxyl group

COOH group on the central carbon of an amino acid

peptide bonds

bond formed between the carboxyl group of one amino acid and the amine group of the next

dipeptide

two amino acids joined together by one peptide bond

polypeptide

a chain of many amino acids joined by peptide bonds

alpha helix

a secondary structure in which the polypeptide chain coils into a spiral held by Hydrogen bonds

beta pleated sheets

a secondary structure in which sections of the chain lie side by side, held by Hydrogen bonds

disulfide bridge

a strong covalent bond between the sulphur atoms in the R groups of two cysteine amino acids.

denaturation

a change in a protein’s 3d shape when bonds are disrupted, for example by high temp or ph, so function is lost

fibrous proteins

A protein made of long, narrow strands. Insoluble in water, with a structural role, for example collagen, keratin, actin and myosin.

globular proteins

A protein with a compact, rounded shape. Soluble in water, with a functional role, for example, enzymes, haemoglobin and myoglobin.

proteomics

The study of the proteome and of the way proteins function and interact.

proteome

The totality of proteins expressed by the genome: all the proteins made by a cell, tissue or organism at a given time.

genome

All of the DNA of an organism. It is the same in almost every body cell.