Nucleic acids, proteins and enzymes Flashcards
Define proteins and polypeptides
Protein- macromolecule made out of amino acid chains
Polypeptide- long chain of amino acids
Difference between monomer and polymer
Monomer- smallest building block of a polymer
Polymer- made up of many monomers
amino acid structure
Central carbon (CH)
amino group
carboxyl group
R-group- different structure for each amino acid, affects the way it bonds to other amino acids (hydrophobic and hydrophillic)
Peptide bond
chemical bond between 2 amino acids
condensation polymerisation reaction
Two monomers join by attaching carboxyl group to amino group, creating water as a by-product
Primary structure
the sequence of amino acids
Secondary structure
when hydrogen bonds are formed between amino acids to create alpha helices, beta pleated sheets or random coils.
Difference between tertiary and quaternary structure
Tertiary- When secondary structure further folds to become a functional 3d protein
Quaternary- Multiple tertiary structure (polypeptide chains) joined together
deoxyribose nucleic acid
double stranded nucleic acid chains (monomers=nucleotides)
Ribonucleic acid
single stranded nucleic acid chain (monomers=nucleotides)
nucleotide structure
Phosphate
Five carbon sugar
Nitrogenous base (GCAT)
Explain why the direction of nucleotides is called 3’ and 5’
3’ and 5’ refer to the carbon number on the sugar, which are ordered in a clockwise direction. RNA has a 5’ to 3’ end because the 5’ carbon is at the top, 3’ is at the bottom
Name all bonds present in DNA and its location
phosphodiester bond (formed via condensation reaction)- sugar-phosphate backbone
hydrogen bond- between base pairs
Name 3 types of RNA and its functions
Messenger RNA- Carries genetic info from nucleus to ribosomes
Transfer RNA- Delivers anticodons to ribosomes
ribosomal RNA- the main structural component in RNA
Gene structure and function
Promoter- enzyme where RNA polymerase binds to (eukaryotes- known as TATA box)
Operator- binding site for repressor proteins, inhibits gene expression
Leader (prokaryotes)-gene regulation
Introns- non-coding DNA that are spliced out in RNA processing
Exons- translated into final protein
Process of transcription
RNA polymerase bind to promoter with the help of transcription factors, DNA unwinds
RNA polymerase creates pre-mRNA from a 5’ to 3’ direction that is complimentary to DNA template strand
RNA polymerase reaches termination sequence synthesis of mRNA is stopped
RNA processing
methyl-G cap is attached to 5’
poly-A tail is attached to 3’
splicing of introns
Translation
mRNA enters ribosomes, is read from 5’ to 3’ from start codon
Its read and tRNA brings amino acids until stop codon is reached
Adjacent amino acids are bonded via condensation reaction
Structural and regulatory genes
Structural- Produces proteins that help with structure or function of cell
Regulatory- Produces regulatory proteins (e.g. repressor proteins)
Explain the repression of trp operon
When trp level is high, trp binds to repressor protein causing conformational change, allowing it to bind to operator. Transcription is prevented
Explain attenuation
When trp levels are high, there is a high presence of tRNA-bound trp. When ribosome arrives at attenuator sequence, 2 trp is added to mRNA, resulting it to fold into a terminator hairpin loop
Identify and describe the function of organelles in the protein secretory pathway
Ribosomes- Synthesises proteins
RER- Folds and transports proteins
Vesicle- Transports proteins
Golgi apparatus- modifies and packages proteins
catabolic vs anabolic reaction
catabolic- breaks molecules and releases energy
anabolic- uses energy to join molecules
