Introduction Flashcards
What is the hereditary information in all cells?
DNA (Deoxyribonucleic acid)
By what mechanism do cells replicate their hereditary information?
Templated polymerisation
What is a DNA nucleotide composed of?
Deoxyribose, a phosphate group, a base (A, T, C or G)
What is an RNA nucleotide composed of?
Ribose, a phosphate group, a base (A, U, C, or G)
What is the intermediary form of hereditary information?
RNA (Ribonucleic acid)
How is DNA expressed?
Transcription and translation
What type of RNA guides the synthesis of proteins?
mRNA (messenger RNA)
What are the specialised chemical properties of RNA?
- it has a flexible backbone so can bend back on itself, which means it can form bonds with itself
- its shape enables it to recognise other molecules by selectively binding to them
- can catalyse chemical changes in certain cases
Define a gene
A segment of DNA that corresponds to the production of a protein or functional RNA molecule
Define ‘genome’
All of the DNA in a cell, coding and non-coding
What are the monomer units of a protein?
Amino acids
What are the two processes by which cells reproduce?
Asexual and sexual reproduction
What happens in asexual reproduction?
A cell divides to form two identical daughter cells that are clones of the mother cell
What happens in sexual reproduction?
Two gametes fuse to form a zygote
How does the genetic alphabet change during translation?
The alphabet changes from a four letter alphabet (A, U, G, and C) to an alphabet of 20 amino acids
The information in the sequence of a messenger RNA molecule is read out in groups of three nucleotides at a time called ______
codons
What are codons?
Nucleotide triplets that code for a specific amino acid
What type of molecules read codons?
tRNA (transfer RNA) molecules
Define diploid
A cell that contains two copies of each gene
Define haploid
A cell that contains only one copy of each gene
What multimolecular machines carry out translation?
Ribosomes
What comprises a ribosome?
Two main chains of rRNAs (ribosomal RNAs) and more than 50 different proteins
What was Gregor Mendel’s experiment?
He bred round seeds (wild-type: RR) and wrinkled seeds (mutant: rr) to produce offspring with the phenotypes Rr. He then self pollinated these plants and found that 1/4 were RR, 1/2 Rr, and 1/4 were rr. The conclusion was that the peas must contain some ‘information’ they pass on.
Define allele
An alternate form of a gene found at the same loci in a stretch of DNA
Define homozygous
A diploid in which the two alleles of a gene are identical (either AA or aa)
Define heterozygous
A diploid in which the two alleles of a gene are different (Aa)
What is a dominant allele?
An allele which always shows its effects on the phenotype if it is present in the genotype
What is a recessive allele?
An allele that only shows its effects on the phenotype if the genotype is absent of a dominant allele
