Genetics Exam 4- Birchler Mizzou

Mitochondria

cellular organelle involved with ATP synthesis and inherited maternally

adjacent I segregation

Type of segregation in a translocation heterozygote that produces meiotic products with deficient and duplicate chromosomal segments (assuming no recombination between the centromere and the translocation breakpoint)

n

the gametic chromosome number.

dideoxynucleotide

type of nucleotide used during DNA sequencing to terminate synthesis

Down Syndrome

human trisomy 21

PCR (polymerase chain reaction)

Method used to amplify many copies of a specific segment of DNA using primers oriented in opposite directions toward each other on the sequence.

Univalent

a chromosome without a pairing partner in meiosis I

Nullisomic

the condition in hexaploids in which a homologous chromosome pair is missing

Electrophoresis

a method of separation of DNA fragments in a gel in an electric field

Autopolyploid

type of polyploid in which all chromosomes are derived from the same species

Histone

subunit of a nucleosome

DNA Ligase

the enzyme that seals together different fragments of DNA during cloning

Homoeologous

in polyploids, non homoeologous chromosomes that are nevertheless very similar in gene content

Euchromatin

regions of a chromosome that stain lightly and that have most of the genes

isoschizomers

Different restriction enzymes that cleave the same DNA sequence

Telomeres

the structures at the very ends of chromosomes that resolve replication

alternate segregation

Type of segregation in a translocation heterozygote that produces meiotic products with all genes represented (assuming no recombination between the centromere and the translocation breakpoint).

nucleosome

The basic unit of chromatin consisting of an octamer of histones.

scaffold

higher order organization in a chromosome to which DNA loops are attached

scaffold attachment regions

a site in the chromosomal DNA that is anchored to the nuclear matrix or scaffold

holds dna loops to scaffold

heterochromatin

Regions of a chromosome that stain deeply, have few genes and have a repressive chromatin environment.

variable number tandem repeats

present at many positions in the chromosomes and the array in each one is virtually unique.

SINE's

short interspersed nuclear elements

LINE's

long interspersed nuclear elements

telocentric

type of chromosome with the centromere very near or at the end

deletion

removal of a chromosomal segment

duplication

change to a chromosome in which part of the chromosome is repeated

inversion

a flip in the order of a portion of a chromosome

translocation

Change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome.

restriction endonucleases

enzymes that recognize specific sequences of nucleotides in DNA and make double-stranded cuts at those sites

Cloning Vectors

-autonomously replicating plasmids into which restriction fragments can be ligated and amplified by growth in bacterial host
-lambda phage which will accept foreign fragments of DNA

Frequency of Cutting

how often do restriction enzymes cut DNA

gel electrophoresis

Method of separation of DNA fragments in a gel in an electric field.

Restriction maps

restriction enzymes can be used to order the recognition sites on a piece of DNA

restriction fragments

A DNA segment that results from the cutting of DNA by a restriction enzyme.

Cloning

isolation of a fragment of DNA and amplification in another organism, usually bacteria.

Ampicillin Resistance

selectable marker in plasmid vector

polylinker

region of DNA containing restriction sites for inserting foreign DNA to be studied

probe

piece of DNA used to identify homologous sequences in a library of plasmids, phage, or artificial chromosomes.

DNA sequencing

the process of determining the precise order of nucleotides within a DNA molecule

dideoxy sequencing

a method of DNA sequencing that uses a template of target DNA for synthesis of new strands, but altered nucleotides are incorporated to stop synthesis at each base in a fraction of the molecules present

oligonucleotide primers

pieces of DNA complementary to the template that tell DNA polymerase exactly where to start making copies

Which direction does DNA synthesis proceed?

5' to 3'`

Restriction Fragment Length Polymorphisms (RFLPs)

Differences in DNA sequence on homologous chromosomes that can result in different patterns of restriction fragment lengths (DNA segments resulting from treatment with restriction enzymes).

Southern Blot

method used to visualize specific restriction fragments in a digest using a radioactive probe after transfer of the digest to a hybridization filter.

polymerase chain reaction (PCR)

A technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and nucleotides.

Microsatellites

simple sequence repeats that are highly variable in length.

chromatin

combination of DNA and protein in the nucleus

histones

chromosomal proteins

octamer

comprised of two copies each of four different histones: H2A, H2B, H3 and H4

solenoid

coil formed by nucleosomes

SAR's

hold loops to the scaffold

Levels of Packing

1) nucleosome
2) nucleosomes coil into solenoid
3) solenoid loops attach to scaffold
4) scaffold and loops form supercoils

euchromatin vs heterochromatin

Euchromatin: less densely packed, most active genes, near ends of chromosomes

Heterochromatin: densely packed, few active genes, near centromere

position effect variegation

if one rearranges a chromosome so that the heterochromatin and euchromatin form a new boundary, the genes in the euchromatin become inactive in some cell lineages

repetitive DNA

several types in multicellular organisms

telomerase

an enzyme that adds telomere repeats to the ends of chromosomes, keeping them the same length after each cell division

Alu

comprises 5% of total human DNA

acrocentric

centromere off center--closer to end than middle (some human chromosomes)

metacentric

type of chromosome with the centromere in the middle

Holocentric chromosome

Type of chromosome with the centromere function throughout its entire length.

asymmetric pairing

duplications can change copy number by _____ followed by recombination
unequal pairing

2 types of inversion

paracentric and pericentric

Paracentric

inverted segment does not include centromere

Pericentric

inversion segment that includes the centromere
do not form dicentric bridges

Translocation

exchange of genetic material between nonhomologous chromosomes

Adjacent-2-Segregation

occurs when homologous centromeres go to the same pole in meiosis

Aneuploid

an addition or subtraction of chromosomes relative to the normal number. Such changes in chromosome number have effects on the phenotype.

Euploid

the normal number of chromosomes of a species or exact multiples of that number

Monosomic

(2n-1) one member of a pair of homologues is missing.

Trisomic

type of aneuploidy when three copies of a chromosome are present

double trisomic

(2n+1+1) has an extra copy of each of two different chromosomes

Nondisjunction

failure of separation of chromosomes or chromatids

maternal effect

maternal gene products determine the early cell divisions of the zygote, which affect coiling.

polyploids

euploid types that have more than two sets of chromosomes

monoploid number

x (number of chromosomes without removing the only copy of a gene)

haploid number

n (number of chromosomes in a gamete)

autopolyploids

multiple sets of chromosomes from the same species. Result from chromosome doubling or failure of meiosis.

allopolyploids

multiple sets of chromosomes but from different (but closely related) species. Result from crosses between species followed by failure of meiosis, which doubles the chromosome number.

triploidy

first level of polyploidy

extranuclear genes

Some traits determined by genomes other than the nuclear genome.

cytoplasmic genes

Genomes present in mitochondria and plastids
genes present in the cytoplasm instead of the nucleus

plastids

Originated as an endosymbiont of a photosynthetic bacterium into eukaryotic cells about 1.5 billion years ago.

Most genes from the bacterial source have been transferred to the nucleus

circular genomes

acentric fragment

the part of a chromosome lost following recombination in a paracentric inversion heterozygote.

monoploid

single set of chromosomes is present in somatic tissue.

colchicine

interferes with mitosis, doubling chromosome number.

aneuploid

an individual with an error in chromosome number; includes deletions and duplications of chromosome segments

euploid

an individual with the appropriate number of chromosomes for their species

haploid

An organism or cell having a single set of unpaired chromosomes.

quadrivalent

The term for the association of four chromosomes together in meiosis in an autotetraploid

trivalent

Three copies of chromosome are synapsed

bivalent

chromosome paired in twos

3' overhang

A telomere has a region at the 3' end that is termed a ________ because it does not have a complimentary strand.

5' overhang

term applied to the product of a restriction endonuclease cleavage in which the 5' phosphate is at the end of the staggered cut that is available for complementary base pairing with other fragments.

dicentric bridge

Recombination within a paracentric inversion loop causes a...

inversion loop

Meiotic pairing configuration produced in an inversion heterozygote.

Centromere

The part of the chromosome that is involved with chromosome movement functions.

Necessary Characteristics of a Plasmid Cloning Vector

1. Origin of Replication
2. Selectable Marker
3. Cloning Site / Polylinker

A linear fragment of DNA is cleaved with the individual restriction enzymes HindIII and SmaI and then with a combination of the two enzymes. Using H for HindII & S for SmaI, draw the restriction map.

Draw a single recombination event within a paracentric inversion loop and show how it resolves during anaphase I.

Check with previous test after drawing "Test 4 Bio 2200"