Glossary 12-16

Question 1

continuous distribution of phenotypes

Answer 1

distribution of phenotypes which approximate a normal curve

Question 2

discontinuous distribution of phenotypes -

Answer 2

phenotypes can be sorted into a few discrete classes

Question 3

contributing allele

Answer 3

an allele which adds to the phenotype

Question 4

non-contributing allele

Answer 4

an allele which does not add to the phenotype

Question 5

multifactorial trait

Answer 5

A trait which results from the interaction of genetic factors and environmental factors.

Question 6

restriction endonucleases

Answer 6

enzymes which cut DNA usually at a specific site

Question 7

palindromic sequence

Answer 7

a sequence that reads the same backwards as forwards eg., the word minim is palindromic

Question 8

recognition sequence

Answer 8

the sequence of bases recognised by s restriction endonuclease within which it will cut

Question 9

plasmid

Answer 9

a circular piece of self replicating DNA found in bacteria. Often carries a gene for antibiotic resistance or tolerance of heavy metals

Question 10

competent cells

Answer 10

cells treated so that they will take up DNA

Question 11

transformation

Answer 11

genetic information is transferred using a vector eg., a plasmid

Question 12

Heterogeneous trait

Answer 12

A phenotype that may arise from mutations in several different genes

Question 13

template/non-template strand

Answer 13

the template strand is the polynucleotide of a gene that acts as the template for RNA synthesis during transcription.

Question 14

coding triplet

Answer 14

this is equivalent to a codon: a triplet of nucleotides that codes for a single amino acid.

Question 15

degenerate

Answer 15

refers to the genetic code and the fact that more than one codon (coding triplet) can code for a specific amino acid.

Question 16

colinear

Answer 16

a gene and the polypeptide for which it codes are related in a direct fashion. The 3’ end of the template strand of the gene corresponds to the amino terminus of the polypeptide.

Question 17

splicing

Answer 17

the removal of introns from the primary transcript of a discontinuous gene. The introns are cut out and the exons are pasted together to form the final transcript.

Question 18

Aminoacyl-tRNA site (A site)

Answer 18

the site on the ribosome where the aminoacyl-tRNA attaches during translation

Question 19

Peptidyl site (P site)

Answer 19

the site on the ribosome at which the tRNA attached to the growing polypeptide is bound during translation.

Question 20

N-terminal/C-terminal

Answer 20

respectively the ends of the polypeptide that carry an NH2 and a COOH
group. The polypeptide grows in the direction from the N-terminal to the C- terminal.

Question 21

de novo mutation

Answer 21

a newly arisen change in a gene

Question 22

Genomic imprinting

Answer 22

sex of transmitting parent produces observable differences in the phenotype, •specific genes are differentially marked during parental gametogenesis

Question 23

Uniparental disomy

Answer 23

Both chromosomes of a pair come from the one parent

Question 24

heterodisomy

Answer 24

Result of non disjunction at anaphase 1

Question 25

polymorphism

Answer 25

two or more distinct forms of a character exist in a Mendelian population of an organism. The frequency of the rarest form cannot be explained by recurrent mutation alone.

Question 26

monomorphism

Answer 26

only one form is found in a Mendelian population.