Biology Exam 1 Vocab

Front 1

centimorgan

Back 1

centimorgan (cM) or map unit (m.u.) is the unit for genetic linkage. It is defined as the distance between chromosome positions for which the average number of chromosomal cross overs in a single generation is 0.01 or 1%

Front 2

genotype

Back 2

genetic constitution of an organism, consists of two alleles per trait

Front 3

phenotype

Back 3

the observable set of traits or set of traits caused by the genotype and environment

Front 4

Self-Fertilization, "selfing"

Back 4

Plants can be manually self fertilized, which ensures no introduction of new alleles into the gene pool

Front 5

Cross-fertilization, "cross"

Back 5

simply mating between male and female gametes from different sources

Front 6

true-breeding/pure-breeding

Back 6

Homozygous for all alleles, an organism that when self crossed will produce offspring identical to the parent

Front 7

monohybrid cross

Back 7

Mendel's cross of a two true-breeding plants that differ on a single trait

Front 8

Reciprocal crosses

Back 8

It is a modified cross where the parents with switched traits are crossed. If same offspring as original cross, then trait is not sex-dependent

Front 9

Mendel's First Law

Back 9

Principle of Segregation - allele pairs segregate during gamete formation. Half the gametes carry one allele, half the gametes carry theo ther

Front 10

locus/gene locus

Back 10

Specific location of a gene on a chromosome

Front 11

Test cross

Back 11

A cross of an individual expressing a dominant phenotype with a individual that is homozygous recessive. The offspring will tell if the individual is heterozygous or homozygous dominant

Front 12

wild-type allele

Back 12

functional allele that predominates, highest frequency in the population in the wild. Generally dominant

Front 13

Loss-of-function mutations

Back 13

mutations of a gene, usually recessively, that causes reduced or nonfunction of the gene, reducing biological functionality

Front 14

null mutation

Back 14

a mutation that results in no protein or a protein with no function in comparison to normal function

Front 15

Mendel's Second Law

Back 15

Principle of independent assortment: pairs of alleles on different chromosomes segregate independently in the formation of gametes

Front 16

Dihybrid Cross

Back 16

Dihybrids are heterozygous for two pairs of alleles at different foci. The cross is a cross between two of these. 9:3:3:1 normally

Front 17

Trihybrid Cross

Back 17

Crossing individuals that are heterozygous for three pairs of alleles at different foci.

Normal: 27:9:9:9:3:3:3:1

Front 18

null hypothesis

Back 18

predicted results and observed data are said to be the same. This is tested via chi-square

Front 19

chi-square

Back 19

Comparing expected and actual data, it's the sum of all (expected-actual)^2/expected. This is translated to p test by looking at degrees of freedom (variables-1). Benchmark for validity is 5%, 0.05

Front 20

Pedigree Rules

Back 20

Offspring are organized left to right in order of increasing date of birth. Fraternal twins are two sides of a triangle, identical are a triangle

Front 21

Homologous chromosomes

Back 21

Chromosomes that contain the same genes. They pair during meiosis, each member is called a homolog

Front 22

Sex Chromosomes

Back 22

Most animals and plants are differentiated in sex by the combination of sex chromosomes. Sexes are generally one morphologically similar pair and one that isn't

Front 23

Centromere

Back 23

Constriction along chromosome length that also connects sister chromatids after division. Its presence is crucial, they will not line up in metaphase without it.

Front 24

Metacentric

Back 24

Chromosome centromere is located in the center

Front 25

Submetacentric

Back 25

Chromosome centromere is located past the midpoint of the chromosome

Front 26

Acrocentric

Back 26

Chromosome centromere is very close to the end of the chromosome, leaving one long arm and almost a bulb

Front 27

Telocentric

Back 27

centromere is at the very end of a chromosome, only one arm exists

Front 28

karyotype

Back 28

complete set of all metaphase chromosomes, often visualized since this is the stage that they are the most condensed

Front 29

Somatic cell cycle phases

Back 29

Interphase (longest), and Mitosis (quite short). Chromosome replication occurs during interphase

Front 30

Sister chromatids

Back 30

After interphase, all chromosomes are replicated. Copies of the exact same chromosome are sister chromatids, held together by the two attached, replicated centromeres. After separating they're known as daughter chromosomes

Front 31

Prophase

Back 31

Chromatids condense and form the double sister chromatid state, nucleolus shrinks or disappears. Mitotic spindle develops outside the nucleus, with centrioles in animals. These centrioles pairs are duplicated and each becomes the focus of an array of microtubules called the ASTER.

Front 32

Prometaphase

Back 32

Developing spindle enters nuclear area. Kinetochore binds to centromeres

Front 33

Kinetochore

Back 33

Specialized protein complex that binds to centromeres during mitosis/meiosis. Kinetochore microtubules from the spindle bind to the kinetochores and manipulate chromosome positioning

Front 34

Metaphase

Back 34

Kinetochore microtubules align all the chromosomes and centromeres along the metaphase plate, 90 degrees to the spindle axis

Front 35

Anaphase

Back 35

The joined centromeres of the two sister chromatids separate and daughter chromosomes move to opposite poles of the cells

Front 36

Telophase

Back 36

Daughter chromosomes group at opposite sides of the cell and begin to decondense and uncoil. Nuclear envelope reforms, spindles disappear

Front 37

Cytokinesis

Back 37

Division of cytoplasm, splits parent cell into two daughter cells. In plants a new cell plate is formed between the nuclei.

Front 38

Prophase I stages

Back 38

leptotene, zygotene, pachytene, diplotene, diakinesis in that order

Front 39

Leptotene

Back 39

"thin threads" - Extended chromosomes begins condensation and are visible as threads

Front 40

Zygotene

Back 40

"paired threads" - Condensation continues, homologous chromosomes find each other and align alongside each other. They synapse and zip-up, aligning the homologs perfectly, base pair per base pair

Front 41

Synapsis

Back 41

Formation of the synaptonemal complex along homologous chromosomes in zygotene which zips them up

Front 42

Pachytene

Back 42

"thick threads" - Once synapsis is completed, crossing over occurs. Condensed AF

Front 43

Bivalent/tetrad

Back 43

The synapsed set of two homologous chromosomes in pachytene

Front 44

Recombinant chromosome

Back 44

Any chromosome resulting from crossing over that differs from the starting chromosome

Front 45

diplotene

Back 45

"two threads" - The centromeres are pulled apart and the bivalent begins to break down. The result of crossing over appears here as chiasmas exist at the locations

Front 46

Chiasma

Back 46

Locations where crossing over occurs, seen in diplotene. Locations where the homologous chromosomes are very closely associated. This prevents the homologous chromosome pairs from separating prior to anaphase

Front 47

Sex chromosomes

Back 47

can be heterogametic or homogametic though those aren't associated with being male or female. Those two terms refer to how what kinds of gametes an organism can make

Front 48

hemizygous

Back 48

a gene is present only once in the individual, with no corresponding homologous gene. Usually sex-linked

Front 49

Crisscross inheritance

Back 49

Male to female offspring or otherwise. Generally evidence of sex linked inheritance

Front 50

Nondisjunction

Back 50

Chromosomes do not segregate appropriately during meiosis, leading to an incorrect number of chromosomes

Front 51

Turner Syndrome

Back 51

Nondisjunction leading to XO females. More or less normal other than shorter than average and less feminine

Front 52

Klinefelter Syndrome

Back 52

Nondisjunction leading to XXY males. Underdeveloped testes, tall, subnormal intelligence

Front 53

XYY Syndrome

Back 53

No real issues. They're male obviously.

Front 54

Epistasis

Back 54

One gene being dependent on other genes. For instance, a null allele albinism trumping any hair color gene. Or a specific dominant phenotype above another

Front 55

Pleiotropy

Back 55

production of superficially unrelated phenotypes by a single allele

Front 56

Lethal allele

Back 56

Almost always recessive alleles that are lethal when homozygous. This results in different ratio of offspring than normal

Front 57

Penetrance

Back 57

% of carriers of an allele that are affected by it

Front 58

Expressivity

Back 58

Degree to which a recessive phentoype is shown, the magnitude of loss of function

Front 59

5-bromo-uracil

Back 59

A base analog to uracil or thymine or something I dunno. It gets incorporated into DN during mitosis which allows us to track its stain.

Front 60

Harlequin chromosomes

Back 60

Sister chromatids that stain differently, usually due to incorporation of a base analog during mitosis

Front 61

ZW Sex determination

Back 61

The convention where males have two identical ZZ sex chromosomes whereas females have ZW. The functionality is opposite that of XY as far as inheritance goes

Front 62

XXX

Back 62

This is usually lethal but in humans results in perfectly normal females for the most part

Front 63

consanguineous mating

Back 63

INCEST IS BAD MMMMKAAAY

Front 64

cis

Back 64

alleles are together on the same chromosome, in coupling

Front 65

trans

Back 65

alleles are on different homologs, in repulsion

Front 66

linkage

Back 66

association of genes together on the same chromosome

Front 67

recombination

Back 67

process of generating nonparental gametic types

Front 68

recombination frequency

Back 68

nonparental gametes/total gametes*100, maxes out at 50%

Front 69

cohesin

Back 69

protein complex responsible for binding sister chromatids or homologous chromosomes in mitosis/meiosis

Front 70

separase

Back 70

enzyme responsible for dissolving cohesin in anaphase, resulting in separation of homologous chromosomes/sister chromatids and breaking apart chiasmata

Front 71

Interference

Back 71

The inhibition of a crossover occurring near another crossover site. Is 1 - coefficient of coincidence. Intereference is complete within 10 map units

Front 72

Auxotroph

Back 72

A genotypic mutation resulting in an organism requiring additional nutritional supplementation compared to the wild type

Front 73

NPD

Back 73

Non-parental ditype - 4 strand double cross over, doubly recombinant, cross over occurs after replication

Front 74

parental ditype

Back 74

tetrad containing two parental genotypes, no crossover

Front 75

tetratype (TT)

Back 75

4 different genotypes, two parental two recombinant from a singular crossover, cross over occurs after replication

Front 76

patroclinous

Back 76

like father in phenotype

Front 77

matroclinous

Back 77

like mother in phenotype

Front 78

polar body

Back 78

discarded product of meiosis

Front 79

Branch migration

Back 79

changes region of hybrid DNA

Front 80

Excision repair

Back 80

eliminates base pair mismatches

Front 81

Chromatid interference

Back 81

the idea that in meiosis, a cross over two chromatids might affect which two chromatids cross over exist. This however, is not true and this is why recomb frequency maxes out at 50%

Front 82

phototroph

Back 82

wild type in respect to nutritional requirement, DOES NOT MEAN its a wild type

Front 83

ade-2

Back 83

encodes an enzyme that synthesizes adenine, mutant spores create red colonies