BIOL214 lecture 11

DNA, RNA, proteins

important molecules for evolution

transcription

happens in nucleus and results in production of RNA from DNA

translation

happens in ribosomes and results in production of proteins

ribosomes

where proteins are made

smooth ER

contains enzymes that produce lipids (like steroid hormones)

rough ER

contains ribosomes that produce many kinds of proteins

Golgi apparatus

finishes, sorts, and ships cell products

DNA

double helix with w strands made up of a long string of nucleotides

mutation

any change to the genomic sequence

ploidy

number of copies of unique chromosomes in a cell

sex chromosomes

a chromosome that pairs during meiosis but differs in copy number between males and females

autosomes

chromosome that does not differ between sexes

gene

a segment of DNA whose nucleotide sequences code for proteins/RNA or regulates expression of other genes

gene expression

is the process by which information from a gene is transformed into a product

RNA polymerase

the enzyme that builds the single-stranded RNA molecule from the DNA template during transcription

hormones

molecular signals that flow through the body and can alter the expression of genes

upstream

towards the 5’ end of the RNA molecule

downstream

toward the 3’ end

gene control region

an upstream section of DNA that includes the promoter region as well as other regulatory sequences that influence the transcription of DNA

repressor

a protein that binds to a sequence of DNA or RNA and inhibits the expression of one or more genes

transcription factor

a protein that regulates the expression of a gene by binding to a specific DNA sequence in association with the gene sequence 

enhancer

a short sequence of DNA within the gene control region where activator proteins bind to initiate gene expression 

microRNA

a group of RNAs that act as post-transcriptional regulators of gene expression and can block transcription

exons

protein coding sequences broken into smaller pieces of coding sequences 

introns

non-coding sequences that split up exons 

RNA splicing

introns are removed

mature mRNA

only exons are included due to RNA splicing and is used to dictate what proteins are produced

alternative splicing

RNA splicing can create multiple proteins from a single gene

prokaryotic gene expression

primarily controlled at the level of transcription

eukaryotic gene expression

controlled at the levels of epigenetics, transcription, post-transcription, translation, and post-translation

mobile genetic element 

a type of DNA that can move around in the genome and plasmids 

plasmid 

a molecule of DNA found most often in bacteria that can replicate independently of chromosomal DNA

vertical gene transfer

the process of receiving genetic material from an ancestor

horizontal gene transfer

the transfer of genetic material between organisms without reproduction. once material is added to the genome, it can be inherited by descent 

pseudogenes

often form after a gene has been duplicated and one or more of the redundant copies lose their function

point mutation

a single base changed from one nucleotide to another (substitution)

insertion

a segment of DNA (single base or more) is inserted into the middle of an existing sequence

deletion

a segment of DNA is deleted accidentally

frameshift mutation 

insertion of 1 or 2 bases changes the codon, modifying all amino acids coded downstream 

duplication

a segment of DNA is copied a second time

inversion

a segment of DNA is flipped around and inserted backwards into its original position

chromosome fusion

2 chromosomes are joined together

aneuploidy

chromosomes are duplicated or lost

genome duplication

leads to increased ploidy

cis-acting element 

a stretch of DNA located near a gene that influences the expression of that gene 

trans-acting element

a sequence of DNA located away from a gene (on another chromosome) that codes for a protein, microRNA, or other diffusible molecules that influence gene expression 

somatic mutation

a mutation that affects cells in the body of an organism; not passed down to offspring in animals

germline mutation

mutation affects the gametes of an individual; can be transmitted from parent to offspring; results in heritable genetic variation

independent assortment

genes are inherited independently of each other; ensures novel combinations of alleles

genetic recombination

during production of gametes, each pair of chromosomes crosses over and exchanges segments of DNA

genotype

the genetic makeup of an individual

phenotype

an observable, measurable characteristic as the manifestation of the genotype of an organism 

polyphenic trait

single genotype produces multiple phenotypes depending on environment

quantitative traits

have continuous distribution of phenotypic variation; influenced by multiple genes, generates a normal distribution 

morphogen

signaling molecule that flows between nearby cells; alters the expression of target genes

phenotypic plasticity

changes in phenotype produced by a single genotype in different environments