Molecular Biology Chapter 1 By David Clark

Front 1

Gregor Mendel

Back 1

Discovered the basic laws of genetics by crossing pea plants.

Front 2

allele

Back 2

One particular version of a gene.

Front 3

gene

Back 3

A unit of genetic information

Front 4

genome

Back 4

The entire genetic information of an individual organism

Front 5

Mendelian character

Back 5

Trait that is clear cut and discrete and can be unambiguously assigned to one category or another.

Front 6

enzyme

Back 6

A protein that carries out a chemical reaction

Front 7

protein

Back 7

A polymer made from amino acids; proteins make up most of the structure in the cell and also do most of the work

Front 8

mutation

Back 8

An alteration in the genetic information carried by a gene

Front 9

regulatory protein

Back 9

A protein that regulates the expression of a gene or the activity of another protein

Front 10

wild-type

Back 10

The "original" or "natural" version of a gene or organism

Front 11

epistatis

Back 11

When a mutation in one gene mask the effect of alterations in another gene

Front 12

genotype

Back 12

The genetic make-up of an organism.

Front 13

null allele

Back 13

Mutant version of a gene which completely lacks any activity.

Front 14

phenotype

Back 14

The visible or measurable effect of the genotype

Front 15

bacteria

Back 15

Primitive single-celled organisms without a nucleus and with one copy of each gene.

Front 16

chromosome

Back 16

Structure containing the genes of a cell and made of a single molecule of DNA

Front 17

diploid

Back 17

Having two copies of each gene

Front 18

haploid

Back 18

Having one copy of each gene

Front 19

haploid genome

Back 19

A complete set containing a single copy of all genes.

Front 20

homologous

Back 20

Related in sequence to an extent that implies common genetic ancestry.

Front 21

ribonucleic acid (RNA)

Back 21

Nucleic acid that differs from DNA in having ribose in place of deoxyribose and having uracil in place of thymine

Front 22

aneuploid

Back 22

Having irregular numbers of different chromosomes

Front 23

copy number

Back 23

The number of copies of a gene that are present

Front 24

homologous chromosomes

Back 24

Two chromosomes are homologous when they carry the same sequence of genes in the same linear order

Front 25

ploidy

Back 25

The number of sets of chromosomes possessed by an organism

Front 26

triploid

Back 26

Having three copies of each gene

Front 27

tetraploid

Back 27

Having four copies of each gene

Front 28

trisomy

Back 28

Having three copies of a particular chromosome

Front 29

dominant allele

Back 29

Allele whose properties are expressed in the phenotype whether present as a single or double copy

Front 30

heterozygous

Back 30

Having two different alleles of the same gene

Front 31

homozygous

Back 31

Having two identical alleles of the same gene

Front 32

partial dominance

Back 32

When a functional allele only partly masks a defective allele

Front 33

recessive allele

Back 33

The allele whose properties are not observed because they are masked by the dominant allele.

Front 34

co-dominance

Back 34

When two different alleles both contribute to the observed properties

Front 35

penetrance

Back 35

Variability in the the phenotypic expression of an allele

Front 36

gametes

Back 36

Cells specialized for sexual reproduction that are haploid

Front 37

modifier gene

Back 37

Gene that modifies the expression of another gene

Front 38

filial generations

Back 38

Succesive generations of descendants from a genetic cross which are numbered F1, F2, F3, etc., to keep track of them

Front 39

meiosis

Back 39

Formation of haploid gametes from diploid parent cells

Front 40

Mendelian ratios

Back 40

Whole number ratios of inherited characters found as the result of a genetic cross.

Front 41

somatic cell

Back 41

Cell making up the body, as opposed to the germline

Front 42

zygote

Back 42

Cell formed by union of sperm and egg which develops into a new individual

Front 43

sex chromosome

Back 43

A Chromosome involved in determining the sex of an individual

Front 44

X-Chromosome

Back 44

Female sex Chromosome; possession of two X-Chromosomes causes female gender in mammals

Front 45

sex-linked

Back 45

A gene is sex-linked when it is carried on one of the sex chromosomes

Front 46

Y-Chromosome

Back 46

Male sex chromosome; possession of a Y-Chromosome plus an X-Chromosome causes male gender in mammals

Front 47

crossing over

Back 47

When two different strands of DNA are broken and are then joined to one another

Front 48

linkage

Back 48

Two alleles are linked when they are inherited together more often than would be expected by chance, usually this is because they reside on the same DNA molecule (that is, on the same chromosome)

Front 49

recombination

Back 49

Mixing of genetic information from two chromosomes as a result of crossing over.

Front 50

linkage group

Back 50

A group of alleles carried on the same DNA molecule (that is, on the same chromosome)

Front 51

Escherichia coli (E. coli)

Back 51

A species of bacterium commonly used in genetics and molecular biology

Front 52

map unit

Back 52

A subdivision that is one hundredth of the length of the bacterial chromosome

Front 53

origin of chromosome (oriC)

Back 53

Origin of replication of a chromosome

Front 54

terminus of replication (ter)

Back 54

The place on any DNA molecule where replication ends

Front 55

partial diploidy

Back 55

Situation in which cell is diploid for only some of its genes

Front 56

plasmid

Back 56

Circular molecule of double stranded helical DNA which replicates independently of the chromosomes of the host cell. Rare linear plasmids have been found.