1B - Flashcards
Describe the structure and shape of protein.
· Proteins have a large variety of shapes which determines their functions.
· Amino acids linked by peptide bonds to form a polypeptide.
· Polypeptide chains fold to form the three-dimensional shape of a protein which is held together by hydrogen bonds and other interactions between individual amino acids.
How is the phenotype of a gene determined?
· Phenotype is determined by the proteins produced as a result of gene expression.
What other factors can influence the phenotype?
· Environmental factors can also influence the phenotype.
What makes up a genome?
· A genome is made up of genes (DNA sequences that code for protein) and other DNA sequences that do not code for proteins.
· What is the genome of an organism?
· The genome of an organism is its entire hereditary information encoded in DNA.
Most of the eukaryotic genome consists of non-coding sequences. What is their function?
Give examples of non-translated forms of RNA
· Non-coding sequences regulate transcription or are transcribed to RNA but never translated to protein.
· Non-translated forms of RNA include tRNA and rRNA.
What are Genes?
· Genes are DNA sequences that code for proteins.
What does the term Gene Expression refer to?
· Gene expression involves transcription and translation of DNA sequences to make proteins.
In eukaryotes are all the genes expressed?
· Only a fraction of the genes in a cell are expressed.
What is the purpose of mRNA?
Where does mRNA get made and where is it transported to?
What is a triplet base and why is it important?
· Messenger RNA (mRNA) carries a copy of the DNA code from the nucleus to the ribosome.
· mRNA is transcribed from DNA in the nucleus and translated into proteinsby ribosomes in the cytoplasm.
· Each triplet of bases on the mRNAmolecule is called a codon and codes for a specific amino acid.
Describe the process of transcription.
- RNA polymerase transcribes DNA into primary mRNA transcripts.
- RNA polymerase moves along one strand of DNA, unwinding and breaking the hydrogen bonds between the bases.
- RNA polymerase then synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing.
- RNA splicing forms a mature mRNA transcript.
Describe the process of translation of the mRNA into a polypeptide.
· tRNA molecules are involved in the translation of mRNA into a polypeptide at the ribosome.
· Translation begins at a start codon and ends at a stop codon.
· Anticodons bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids.
· Peptide bonds join the amino acids together.
· Each tRNA then leaves the ribosome as the polypeptide is formed.
What are the 3 types of RNA called?
Describe the structure of RNA.
· The three types of RNA involved in transcription and translation are:
mRNA, rRNA and tRNA
· RNA is single strandedand is composed of nucleotides containing ribose sugar, phosphate and one of four bases: cytosine, guanine, adenine and uracil.
Describe the shape of tRNA.
What does the tRNA carry to the ribosome?
Describe the function of ribosomal DNA
· Transfer RNA (tRNA) folds into a 3-D shape due to complementary base pairing.
· A tRNA molecule has an anticodon (an exposed triplet of bases) at one end and an attachment site for a specific amino acid at the other end.
· Each tRNA molecule carries its specific amino acid to the ribosome.
· Ribosomal RNA (rRNA) and proteins form the ribosome.
What is RNA splicing?
· The introns of the primary transcript of mRNA are non-coding regions and are removed.
· The exons are coding regions and are joined together to form mature RNA transcript.
· The order of the exons is unchanged during splicing.
