Genetics Test 4

Front 1

nucleosomes

Back 1

Subunits of chromatin composed of DNA and 8 Histones. H2A, H2B, H3, H4

Front 2

histones

Back 2

A type of protein that forms the unit around which DNA is coiled in the nucleosomes

Front 3

scaffold

Back 3

Central core of a chromosome to which loops of DNA and protein attach.

Front 4

scaffold attachment regions

Back 4

Also called SARs. Hold loops of DNA and protein to scaffold

Front 5

heterochromatin

Back 5

Heavily staining portions of a chromosome. Densely packed, have few active genes, near centromere

Front 6

euchromatin

Back 6

Lightly Staining portion of chromosome. less densely packed, most active genes, near ends of chromosomes.

Front 7

centromere

Back 7

Site of attachment of spindle fiber to the chromosome.Have been successfully cloned in yeast and are only 125 nucleotides in length. Human centromeres are about 2-3 million base pairs

Front 8

telomere

Back 8

Found at the end of chromosomes. Resolve a problem with DNA replication at the ends of chromosomes. Form Hairpin loops that act as primer for replication. Consists of hundreds of copies of TTAGGG. This is added sequentially by telomerase.

Front 9

variable number tandem repeats

Back 9

15-100 nucleotides repeated for 1-5 kb. Present in many positions in chromosome and each is unique. Use to make DNA fingerprint for forensics

Front 10

SINEs

Back 10

Short interspersed elements. Transposable elements of DNA that make up a substantial piece of our genome

Front 11

LINEs

Back 11

Long interspersed elements. Transposable elements related to retroviruses. There are about 20,000 to 40,000 copies in human genome.

Front 12

telocentric

Back 12

Structure of chromosome where centromere is located near the end. (mice)

Front 13

acrocentric

Back 13

Structure of chromosome where centromere is closer to the end than the middle (some human chromosomes)

Front 14

metacentric

Back 14

Structure of chromosome where centromere is near the middle (some human chromosomes)

Front 15

acentric

Back 15

A chromosome that has lost a centromere

Front 16

holocentric

Back 16

Chromosome has diffuse centromeres that have spindle attachments at many sites (scorpions, wood rushes)

Front 17

deletion

Back 17

Type of chromosome rearrangement where a piece is missing. Usually lethal when homozygous. No recombination in the region spanning the deletion. Can never revert back to normal. phenotypic expression of recessive alleles on a normal homologue for several close genes.

Front 18

duplication

Back 18

Type of chromosome rearrangement where there are two copies of the same piece.

Front 19

inversion

Back 19

Chromosomal segment that is rotated 180 degrees. Forms an inversion loop when paired iwth a normal sequence chromosome.

Front 20

translocation

Back 20

Refers to the exchange between nonhomolgous chromosomes

Front 21

asymmetric pairing

Back 21

allow Duplications to change copy number when followed by recombination.????

Front 22

inversion loop

Back 22

Formed during inversion

Front 23

paracentric inversion

Back 23

inverted segment does not include a centromere

Front 24

pericentric inversion

Back 24

Inverted segment includes a centromere

Front 25

dicentric bridge

Back 25

Formed during recombination in a paracentric inversion loop. Bridge breaks and the fragment is lost preventing the recovery of recombinants

Front 26

acentric fragment

Back 26

fragment lost during paracentric inversion

Front 27

alternate segregation

Back 27

alternate centromeres go to the same pole. All genetic material present in all gametes. (AB' vs. A'B)

Front 28

adjacent 1 segregation

Back 28

Adjacent centromeres go together (AB vs. A'B'). Creates duplications and deficiencies that are usually inviable.

Front 29

adjacent 2 segregation

Back 29

occus when homologous centromeres go to the same poles in meiosis

Front 30

euploid

Back 30

Number number of chromosomes or chromatids characteristic of a species or exact multiples of that number.

Front 31

aneuploid

Back 31

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

Front 32

monosomic

Back 32

2n-1. One member of a pair of homologes is missing. Lethal in almost all animals. Can survive for some chromosomes in diploid plants, although they are shorter. Can survive in polypliud plants

Front 33

trisomic

Back 33

2n+1. Lethal in animals, Possible in plants but gives much less vigorous plants. In meiosis two of the three chromosomes pair. The segregation in a trisomic gives about 1/2 trisomic 1/2 normal. The unpaired centromere often does not attach and is lost

Front 34

double trisomic

Back 34

2n +1+1.

Front 35

nondisjunction

Back 35

failure of separation of chromosomes or chromatids. During meiosis n+1 or n-1 formed. During fertilization becomes 2n+1 or -1

Front 36

down syndrome

Back 36

characterized by mental retardation, epicanthic fold on eyes, short, hands have crease all the way across, large tongue, infertile males, short lived. Caused by trisomic

Front 37

monoploid

Back 37

Have only one set of chromosomes. Exist in nature as male bees, wasps, ants.

Front 38

polyploid

Back 38

Euploid sets that have more than 2 sets of chromosomes

Front 39

haploid

Back 39

(n) number of chromosomes in gametes.

Front 40

colchicine

Back 40

Doubles chromosome numbers by interfering with the spindle.

Front 41

autoploid

Back 41

sets of chromosomes from the same species

Front 42

alloploid

Back 42

Sets of chromosomes from different species

Front 43

homoeologous

Back 43

related chromosomes from different species. Means only partially homologous.

Front 44

triploidy

Back 44

First level of polyploidy. Can be caused by acceptance of 2 sperm by an egg, gametes that result from a failed meiosis, cross of tetraploid x diploid

Front 45

quadrivalent

Back 45

If all chromosomes are associated in meiosis. |x| - two chromosomes with middle ones connected to both outside ones

Front 46

univalent

Back 46

one chromosome in meiosis

Front 47

trivalent

Back 47

Three chromosomesin meiosis. | X

Front 48

bivalent

Back 48

If four chromosomes are paired in 2s called during meiosis || ||

Front 49

nullsomic

Back 49

A species with 3 genomes that can tolerate the loss of one

Front 50

x

Back 50

represents the monoploid number. Is the smallest possible number of chromosomes allowed without deleting any.

Front 51

n

Back 51

Number of chromosomes in a species

Front 52

extranuclear genes

Back 52

Genomes not located in the nucleus

Front 53

cytoplasmic genes

Back 53

Genes that reside in organelles. In mitochondria or plastids

Front 54

mitochondria

Back 54

Organelles whose main function is production of ATP. energy source of the cell

Front 55

plastids

Back 55

Plant organelles. Can be chloroplasts, chromoplasts, or Leucoplasts.

Front 56

cytoplasmic segregation

Back 56

During development in plants random distribution of normal and mutant plastids can give rise to independent sectors that fully exhibit each phenotype.

Front 57

maternal effect

Back 57

When phenotype of mother determines phenotype of progeny. Shows mendelian segregation in the F3

Front 58

DNA ligase

Back 58

Seals gaps made by DNA polymerase when transposable elements insert into a new location

Front 59

plasmid

Back 59

DNA molecule that can replicate independently of chromosomal DNA. Used in PCR

Front 60

isoschizomers

Back 60

Different enzymes that cleave the same DNA sequence

Front 61

3' overhang

Back 61

Can be generated by cleavage and has 3' end sticking out

Front 62

5' overhang

Back 62

Can be generated by cleavage and has 5' end sticking out

Front 63

electrophoresis

Back 63

Seperates cleaved fragments based on their size

Front 64

ethidium bromide

Back 64

Combines with DNA and gives off light when put under UV. Allows fragments to be seen.

Front 65

restriction fragment

Back 65

Fragments of DNA made by restriction endonucleases. CAn be used to order recognition sites on a piece of DNA

Front 66

restriction map

Back 66

Map of DNA determined by fragments of DNA.

Front 67

gene library

Back 67

Collection if

Front 68

yeast artificial chromosome

Back 68

Plasmids that hold 200-500 kb. BACs are more stable

Front 69

transposon tag

Back 69

Tag on TE used to recognize a transposition into a gene to make a mutation

Front 70

chromosome walk

Back 70

Piecing together of small fragments of chromosome using restriction sites on each fragment to match them up.

Front 71

dideoxynucleotide

Back 71

Strand of DNA without OH on the 3' end. Paired with DATP,DCTP,DGTP,DTTP. Seperate each into a lane on a gel and where it stops is the order of the DNA

Front 72

restriction fragment length polymorphism

Back 72

RFLP. Differences between two fragments of DNA. Caused by nucleotide change, deletion or insertion. Can be used to compare.

Front 73

Southern blot

Back 73

Allows you to examine the length a a particular segment of DNA among the thousands produced by restriction endonuclease. Denatured DNA fragments probed with radioactive DNA fragment homologous to gene you are looking for. x-ray shows location of radioactivity.

Front 74

polymerase chain reaction

Back 74

PCR. Used to make millions of copies of a small amount of DNA. Short primers initiate DNA synthesis.