genetics chapter 14

Gene Mutations, DNA Repair, and Transposition

mutation

mutation

inherited change in genetic info

gene

___ mutations - changes in sequence in or around a gene

somatic

mutations which are passed from parent to daughter cells through mitosis

germ line

mutations which are passed from parent to child through gametes. can be x or y mutations

point

____ mutations are alterations of a single nucleotide

transition

_____ mutations are a type of point mutation where a purine replaces a purine or vice versa

transversion

_____ mutations are a type of point mutation where a pyramidine replaces a purine or vice versa

frameshift

______ mutations happen when a nucleotide is inserted or deleted

coding

mutations where there is a change in the amino acid or protein due to a point or frameshift mutation

missence

_____ mutations are a type of coding mutation where one AA (Ser) is usually coded but instead another AA (Leu) is coded

nonsense

______ mutations are a type of coding mutation where one AA (Ser) is usually coded but instead a stop codon is coded

silent

______ mutations are a type of coding mutation where on the AA level, nothing changes

neutral

A ________ mutation is one where you have a different AA but on the protein level nothing changes

loss

___ of function mutations are ones where the protein does it’s work improperly or not at all (tend to be recessive)

dominant

_____ negative is where a mutant may interfere with wild-type or one wild type is not enough (haploinsufficency)

gain

___ of function mutation is one where it produces a new trait, tends to be dominant

supressor

______ mutations are mutations which follow previous mutations to restore the null (intra/intergenic)

intragenic

a suppressor works within the same gene

intergenic

a suppressor works from outside the gene

visible

easily observed phenotypic change

nutritional

a phenotypic change where it leads to a loss of ability to synthesize an amino acid or vitamin

biochemical

a phenotypic change in a biochemical pathway

behavioral

a phenotypic change in behavioral patterns

regulatory

a change in gene expression, can disrupt an entire pathway

lethal

a phenotypic change which dispirits an essential process

conditional

phenotypic change only under certain environmental conditions

temperature

______-sensitive is a type of phenotypic change only seen at different temperatures

spontaneous

_______ mutations are ones that occur with no known cause

induced

______ mutations are ones that occur from outside factors (artificial or natural)

mutation rate

how often a mutation will occur in a singe generation

tautomer

a different form of an amino acid (change is spontaneous) different hydrogen bonds in amino acids, point mutation

slippage

replication ______ is when one strand either slips forward and skips a nucleotide or it slips backward and reads the same nucleotide twice

repetitive

______ sequences lead to unequal crossing over or replication slippages

unequal

_____ crossing over is when the homologs line up wrong due to repetitive sequences

depurination

loss of a nitrogenous base (commonly replaced w A)

deamination

loss of an amino group

mutagenic

reactive forms of oxygen (such as oxygen radicals) can be _______

artificially induced

When you introduce radical oxygens, it is ___ __ ______ meaning that it is from outside the cell and not natural.

mutagens

Chemical ______ can do many tasks such as: adding alkyl groups, causing the loss of an amine group, or adding a hydroxyl group

base analog

____ _ ______s mimic nitrogenous bases, not the nucleotide, and look just like one, can be integrated into DNA and then change shape which causes issues

intercalating

______ agents are mutagenic and wedge themselves into DNA and change the backbone. Electrophoresis uses Ethidium which can move up the gel and is cancerous

naturally induced

UV energy mutating a skin cell is __ __ ______ and can be sterilizing, it leads to pyramiding dimers

interstrand

_____ cross-linking is mutagenic and toxic. It happens when two strand covalently link to each other and block replication. Can be used on cancer cells

2

How many strands of DNA are required for repair?

ways

DNA repair can be corrected in multiple different ___

mismatch

____ repair occurs when a methyl group conjoined with a mismatch repair complex, scans the DNA and changes the non-template DNA (marked by the GATC) and keeps a methyl group on the template CTAG

direct

____ DNA repair happens when there is a methyl transferase and a CH3 group release

dimer

when DNA is damaged, a ____ can form (like a lump in the DNA but the pyramindines bond together (sideways bond)

photo activation

___ _______ repair happens when a PRE breaks the covalent bonds that link the pyramidine dimers

Base Excision

___ _ _____ repair is when the base is damaged and a DNA polymerase and ligase come in and fix it

NER

___ stands for Nucleotide Excision Repair, happens when you cut out an entire strand around the mutation and DNA polymerase comes in with ligase and forms a whole new strand

ds Break

_ _____ Repair is when the homologous sisters use each other to repair, the 3’ broken end will invade the other sister and DNA synthesis occurs across the broken strand and heteroduplex resolved

SOS

___ repair happens after replication when there’s a lesion, the replication skips over region and two nucleotides antiparallel and complementary join the replicated skipped strand, and the place where the two came from is sealed by DNAP and ligase

syndromes

Defects in DNA repair can lead to ______

Ames

The _____ test is used to identify potential mutagenes. If adding a chemical to this bacteria, will is change from his- to his+? if it does, it is mutagenic.

carcinogenic

If a chemical is mutagenic, chances are that it is also _______

transposable

_____ elements or transposons, are highly repetitive and ‘mobile’ genes. can cause mutations by ‘jumping’ into a gene causing rearrangements

50

__% of the human genome is transposons.

flanking direct

__ __ ____ repeats are not a part of the element and do not hop with the element

terminal inverted

_____ _______ repeats: at the ends of some elements, are the inverted complement of one another, important in the movement of the gene

stagger

The transposon cuts two ends making a _____ in the DNA where the transposable element sticks in the middle and DNAP comes in a fills the gaps making flanking direct repeats

Barbra McClintock

discovered transposable elements from maize corn, phenotypic pigmentation.

Ac

The element which has the transposase meaning it can move by itself.

Ds

The element which does not make transposase (deleted) and cannot move by itself

larger

The earlier the transposition in a kernel’s life, the ____ the spot of purple

inactive

Transposons are mostly _____ in humans, more than 50-40x DNA is from transposons than proteins

RNA

__ intermediates are used by retrotransposons. reverse transcriptase!

reverse transcriptase

__ _ _____ is the enzyme used by retrotransposons as well as integrase

RT

LINEs encode their own __ which means they can move into DNA all by their own

SINE

____s cannot encode their own reverse transcriptase meaning they must take it from LINE. Has the Alu family which is 10% of the genome

mutagenic

transposable elements are _____ meaning that they insert themselves into genes and disrupt gene function.

8

Three different LINEs are known to disrupt factor _ gene (huge and can be easily disrupted)

BRAC2

____ gene with an All insertion can cause a predisposition to breast cancer

copy

a high ___ number can lead to genome rearrangements (inversions, deletions, unequal crossing over)

copy, paste

retrotransposons ________and ______ while transposons just cut paste

telomeres

some LINEs act as repeated ends of ______, which keeps the ends at the proper length

recombinase

A TE which has become essential for us, cuts DNA

good

Some mutations from TEs are ___ (Genetic Variation Hypothesis)

Selfish

The ____ DNA hypothesis says that TE serves no purpose other than to spread