U2 Definitions Flashcards
DNA
Polymer with 2 strands composed of sequences of the nucleotide bases
Chromosome
2 molecules of DNA packaged by histone proteins
–> Each half (unreplicated) chromosome has ONE DNA molecule
–> We have 2 of each chromosome
–> 23 Pairs (46 altogether)
Duplicated Chromosome
–> X shape
–> 2 molecules of DNA
Chromatid
1/2 of the chromosome
–> ONE dna molecule
Gene
A segment of DNA on a chromosome that is transcribed
–> The information: they DO NOT do make anything (the recipes)
–> Have both coding and non-coding regions
Transcription
The process of producing an RNA molecule from a DNA segment
–> RNA polymerase makes an RNA copy of the DNA = mRNA
Allele
A version of a gene
–> Each chromosome pair has the same genes but may differ in alleles
–> One of the pair contains alleles inherited from mother and other in the pair contains alleles inherited from father
Homozygous
Two alleles for a gene are the same
Heterozygous
Two alleles for a gene are different
Genotype
Genetic makeup
–> DNA sequences of chromosomes and the 2 alleles carried for genes
Phenotype
Any observable characteristics or trait of an organism/cell
Translation
Converting mRNA sequence to an amino acid sequence
–> Ribosomes translate the mRNA to produce chains of amino acids –> Leads to protein folding
Protein Folding
Results in final conformation of protein
Process of getting from genotype to phenotype
Genotype —-> Protein —-> Phenotype
Coding vs Non-Coding Regions
Coding = Encodes for gene products
Non-Coding = Instructions for WHEN, HOW MUCH, and IN WHAT cells to transcribe genes
Proteins
Polymers of amino acids connected by peptide bonds
Non-Coding Region Functions
Determine the amount, the time, and the location (in what cells) of transcription
–> Essentially determines level of expression of a gene (which is determined by amount of protein)
Allele Transcription
BOTH alleles are transcribed, just some are transcribed more than others –> Producing different amounts of proteins (difference between recessive and dominant)
Gene Regulatory Switch
A short sequence (~5-20 base pairs) of DNA in the non-coding region of a gene
–> Where TRPs bind
–> The “light switch”
Transcriptional Regulatory Protein
TRP: Proteins that bind to gene regulatory switches that either activating or repressing transcription
Cell Diversity
All cells have the same gene regulatory switches, but not all cells have the same TRPs needed to interact with those switches
–> Leads to cell differentiation
“Dimmer Switch” of Gene Regulatory Switches
Most genes are regulated over a range of expression levels between repressed, intermediate, and high levels of expression
–> Due to the fact that gene regulatory switches usually have multiple bindings sites for TRPs
Binding of TAP to Gene Reg. Switch
Enables RNA polymerase to interact with coding region –> Activates transcription
Promoter
Specific coding sequence adjacent to beginning of a coding region
(regulatory switch does not need to be next to promoter)
Mutation
A change in the nucleotides of a DNA molecule
“The factory of variation production” –> Main source of genetic variation
–> Mutations occur at every cell division
–> Occur randomly and are UNAVOIDABLE (majority of mutations are NOT from radiation/environment)
Point Mutations
Most common type of mutation: Single nucleotide changes
Duplication Mutations
One or more copies of a DNA segment is produced, duplicating a sequence when it shouldn’t be
Germ-Line Mutations
Mutations that occur in cells giving rise to gametes
–> These mutations are passed down to offspring
Somatic Mutations
Mutations that occur in body cells (not gametes)
–> These mutations are NOT passed down to offspring
Mitosis
Process by which a cell divides into two identical daughter cells
–> Diploid daughter cells
Meiosis
The process by which humans and most animals produce gametes
–> Daughter cells are haploid (only contain one of two alleles)
Recombination
Creates new combinations of alleles in gamete DNA
–> A physical exchange of DNA between copies of the same chromosome
Independent Assortment
Creates diverse recombinations of chromosome copies among gametes produced by an individual
–> Occurs in meiosis to produce genetic variation
