1.3 Flashcards
A cells _________ is determined by the proteins that are synthesised when the genes are expressed. These are influenced by ______ and ____-_______ environmental factors
Phenotype
Intra
Extra-cellular
A cells ________ is determined by the sequence of DNA bases in its genes
Genotype
The phenotype is determined by _______ produced as a result of gene expression. Only a fraction of the genes are expressed in a particular cell
Proteins
Gene expression is controlled by the regulation of _________ and ________
Transcription
Translation
Formation of polypeptide chains
- Hydrogen bonds form between certain amino acids in a polypeptide chain causing the chain to become coiled/ folded
- As the protein folds, interactions between other amino acids can occur, more hydrogen bonds are formed as sulfur bridges
- These bonds are important as they cause the protein to adopt the 3D shape needed to perform its function
- A polypeptide may also need to be cut to become active or be combined with another polypeptide
- Non-protein components can also be required such as carbohydrate or phosphate group
Vital proteins in living cells include;
Enzymes
Structural proteins
Hormones
Antibodies
What is RNA
Stands for RiboNucleic Acid, it is a similar molecule to DNA. It is a single stranded molecule composed of subunits called nucleotides. Each nucleotide is made up of ribose sugar, a phosphate and a base (Uracil replaces Thymine)
Types of RNA
Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)
________ is the formation of ______ in the ________, using DNA as a template. ________ is formed in the ________ from free nucleotides and carried a copy of the DNA code from the nucleus to the ribosome (where protein synthesis occurs)
Transcription mRNA Nucleus mRNA Nucleus
_________ is the formation of a _______ from mRNA at a ________
Translation
Protein
Ribosome
Transcription definition
The synthesis (copying) of mRNA strand from a section of DNA
A _______ is a region of DNA in a gene where transcription starts
Promoter
In eukaryotes long stretches of DNA exist which don’t code for proteins - called ______. Coding regions are called ________
Introns
Exons
Splicing: the _______ are cut out from the primary transcript of mRNA and the ______ are ________ ________ to form mRNA with continuous sequences of nucleotides coding for proteins. The ______ _____ then passes out of the nucleus via a poor in the nucleus membrane into the cytoplasm
Introns
Exons
Spliced together
Mature mRNA
Definition of translation
Is the synthesis of protein as a polypeptide chain under the direction of mRNA
Binding sites on a ribosome - 3 sites - and each sites function
Site A - holds the tRNA carrying the next amino acid to be joined to the growing chain by a peptide bond
Site P - holds the tRNA carrying the growing polypeptide chain
Site E - discharges a tRNA from the ribosomes once it’s amino acid has become part of the polypeptide chain
Write notes in the translation of mRNA in protein synthesis (7)
- mRNA contains the codon and tRNA contains the anticodon
- The ribosome binds to the 5’ end of the mRNA
- The anticodon allows tRNA to carry a specific amino acid
- tRNA transports amino acid to the ribosome from the cytoplasm
- Site A holds the tRNA carrying the growing polypeptide chain
- Site P holds the tRNA with the next amino acid to be joined
- Site E discharges the tRNA from the ribosome
- A peptide bond forms between each amino acid
- Amino acids form a polypeptide Chaim
- tRNA is recycled/ picks up another amino acid in the cytoplasm
A polypeptide chain may need to be ______(_______) by _______ to become active
Cut (cleaved)
Enzymes
Describe the role of RNA in protein synthesis (7)
- mRNA carries information/ code (for proteins) from the nucleus/ from DNA
- mRNA attaches to ribosome
- Three bases on mRNA is a codon
- tRNA transports amino acids to ribosome
- tRNA transports specific amazing acids
- Three bases on tRNA is an anticodon
- Codons math/ pair with their anticodon a
- Joins/ adds correct amino acid onto growing protein/ polypeptide
- Sequence of bases/ codons of mRNA gives sequence of mini acids
