AP Bio - mutations and genes

changes in the genetic material of a cell, which can alter phenotypes

mutations

primary source of genetic variation

mutations

large scale mutations

chromosomal changes

small scale mutations

nucleotide substitutions, insertions, or deletions

changes in a single nucleotide pair of a gene

point mutations

the replacement of one nucleotide and its partner w/ another pair of nucleotides

substitution

still codes for the same amino acid

• redundancy

silent

change results in a different amino acid

missense

change results in a STOP codon

nonsense

when the reading frame of genetic information is altered

• small scale mutation

frameshift mutation

insertions and deletions have:

• small scale mutations

disastrous effects to resulting proteins

when chromosomes do not separate properly in meiosis

ex: down syndrome

nondisjunction

a segment of one chromosome moves to another— exchange between nonhomologous pairs

translocation

a segment is reversed

translocation

a segment is repeated

duplication

a segment is lost

deletion

any time __________ occur, they are subject to natural selection

• genetic changes can sometimes enhance the survival and reproduction of an organism

mutations

prokaryotes can exchange genetic material through:

horizontal gene transfer

if there is a mutation beneficial to the survival and reproduction of a prokaryote, it can be:

transferred

uptaking of DNA from the environment

transformation

viral transmission of genetic material

transduction

cell to cell transfer of DNA

conjugation

movement of DNA segments w/in and between DNA molecules

transposition

both DNA and RNA can be manipulated through

genetic engineering

a technique used to separate DNA fragments by size

• DNA is loaded into wells on one end of a gel and an electric current is applied

  • DNA fragments are positively charged

gel electrophoresis

a method used in molecular biology to make several copies of a DNA segment

• segments of DNA are amplified

• results can be analyzed using gel electrophoresis

PCR

a type of protein found in chromosomes

histones

a group of histone proteins with nucleotides wrapped around it, fundamental unit of chromatin

nucleosomes

DNA is _______ charged and histones are _________ charged

negatively, positively

chromatin must be _________ to expose the promoter so RNA polymerase can bind to it

decondensed

promoted decondensed chromatin in histones

• active transcription

acetylation

• promotes condensed chromatin

  • associated with transcriptional repression (most of the time)HA

methylation

histone acetyltransferases

HATs

histone deacetylases

HDACs

cause chromatin to decondense

HATs

cause chromatin to condense

HDACs

a group of proteins that use energy from ATP hydrolysis to shift nucleosomes on DNA so as to expose or hide DNA sequences from transcription factors

chromatin remodeling complexes

alternatively spliced RNA

isoform

degradation of an mRNA molecule or inhibition of its translation following its binding by a short RNA whose sequence is complementary to a portion of the mRNA

RNA interference

a small, single-stranded RNA associated with a small, single-stranded RNA associated with proteins in an RNA-induced silencing complex

microRNA

a codon that is three nucleotides long and encodes for 1 amino acid

triplet code

all but two amino acids are encoded for by more than one codon

redundant

one codon never codes for more than one amino acid

unambiguous

codons are read one at a time

non-pverlapping

all codons specify the same amino acids in all organisms, with a few minor exceptions

universal

if several codons specify the same amino acid, the first two bases are usually identical

conservative

some mutations increase fitness of organism

beneficial

no effect on fitness

• ex: silent mutation

neutral

many mutations lower fitness— but depends on the environment

• ex: most point mutations

deleterious

segments of a broken chromosome may be flipped and rejoined

inversion

correct # of chromosomes

euploidy

change in chromosome # resulting from nondisjunction

aneuploidy

(2n-1) when an individual has one type of chromosome when they should have 2

monosomy

(2n+1) when an individual has 3 chromosomes when they should have 2

trisomy

the cell could make mRNAs only for proteins it needs

• provides a slower response, but conserves resources

transcriptional control

the cell can prevent the mRNAs for unneeded proteins from being translated

translational control

after translation, many proteins have to be activated by chemical modification

• ex: phosphorylation

• fast, but energetically expensive

post-translational control

describes when a protein is synthesized all the time/ constantly

constitutively