Genes and Genomes Flashcards
Cytoplasm
Inner contents of a cells between you the nucleus and plasma membrane
Plasma membrane
Double-layer structure of lipids and proteins that surrounds the outer surface of cells
Organelles
Structures in the cell that perform specific functions
DNA
A nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms
Transformation
The uptake of DNA by bacterial cells
Gene
A sequence of nucleotides that provides cells with the instructions for the synthesis of a specific protein or type of RNA
Chromosomes
Highly cooled and tightly condensed package of DNA and protein
Chromatin
Strings of DNA and DNA-binding proteins called histones
Mitosis
One cell divides to form two daughter cells, each with an identical copy of the parent cell DNA (2n)
Semiconservative replication
Replication occurs in such a manner that, after replication, each helix contains one original (parental) DNA strand and one newly synthesised DNA strand
Steps in DNA replication
- Unwinding the DNA
- Adding short segments of RNA
- Copying the DNA
Helicase
An enzyme breaks the hydrogen bonds holding the two DNA strands (unzips DNA)
Primase
An enzyme that adds RNA primers (RNA primers start the replication process)
DNA Polymerase
Enzyme binds to the RNA primers. Uses nucleotides to synthesise complementary strands of DNA
Mutation
Change in the nucleotide sequence of DNA
Inherited mutations
Those passed onto offspring through gametes. Mutation is present in the genome of all the offspring’s cells
Acquired mutations
occur in the genome of somatic cells
Origins of replication
Regions of DNA in which the separation of complementary strands occurs
Point mutation
Changes in a single nucleotide
Silent mutation
Mutation changes codon into another codon which codes for the same amino acid
Missense mutation
Mutation changes codon into codon that codes for a different amino acid but does not change the structure or function of the protein
Nonsense mutation
Changes a codon into a stop codon, shortened proteins
Transcription
Genes are copied from DNA code to RNA code
Translation
RNA code is used to sequence amino acids to form a protein
Transcription steps
1) Initiation
2) Elongation
3) Termination
Genetic code
Universal language of genetics used by virtually all living organisms
Function of mRNA
Exact copy of gene. Carries genetic code from nucleus to cytoplasm
Function of rRNA
Component of ribosomes, organelles responsible for protein synthesis
Function of tRNA
Transports amino acids to ribosome. Contains an anticodon which binds to mRNA in order to sequence amino acids.
Ribosome
Organelle in which mRNA is translated to protein
Gene regulation
How genes are turned on and off in response to different signals
Gene expression
Production of mRBA by a cell
DNA binding motifs
Folded structural arrangement of amino acids that interact directly with the DNA
Cis-acting elements
DNA sequence that can effect the expression of its own gene
Trans-acting elements
Proteins that bind indirectly to cis- acting elements and regulate transcription initiation
Function of silencer
To repress transcription when interacting with certain proteins
Operons
Cluster of several related genes located together and controlled by a single promoter
Epigenome
Modifications to chromatin structure which do not involve changes in DNA sequence
Name three modification type of epigenome
Phosphorylation
Acetylation
Methylation
5’ end capping
The triphosphate structure at the 5’ end of the mRNA is replaced by a “cap”
