Cell Biology and Genetics

Question 0

Define aneuploidy

Answer 0

The condition in which the chromosome number of the cell is not an exact multiple of e haploid number

Monosomies and trisomies are examples of aneuploidy

Question 1

Define allele

Answer 1

One of series of alternative versions of a gene or DNA sequence at a given locus

Question 2

Define antisense

Answer 2

A piece of nucleic acid, typically created in the lab, which has a sequence exactly opposite to an mRNA molecule made by the body

Antisense can bind tightly to its mirror image mRNA, preventing a particular protein from being made

Question 3

Define autosomal dominant

Answer 3

A trait or disease that is produced when only one copy of a polymorphism or mutation is present on an autosome

Question 4

Define autosomal recessive

Answer 4

A trait or disease that is produced when two copies of a polymorphism or mutation are present on an autosome

Question 5

Define autosome

Answer 5

Any chromosomes other than sex chromosomes

Question 6

Define cell

Answer 6

The cell is the basic unit of life

If it is to survive, each cell must maintain an internal environment that supports its essential biochemical reactions, despite changes in the external environment

Therefore, a selectively permeable plasma membrane surrounding a concentrated aqueous solution of chemicals is a feature in all cells

Question 7

Define a clone

Answer 7

A member of a group of cells that all carry the same genetic information, and which are derived from a single ancestor by repeated mitosis

Question 8

Define compound heterozygote

Answer 8

An individual with two different mutant alleles at the same locus

Question 9

Define consultand

Answer 9

An individual seeking, or referred for, genetic counselling

Question 10

Define exon

Answer 10

Region of a gene containing DNA that codes for a protein

Question 11

Define gamete

Answer 11

The reproductive cell formed by meiosis, containing half the normal chromosome number

Question 12

Define genome

Answer 12

This is the entire genetic complement of a cell

Question 13

Define genotype

Answer 13

This is the genetic constitution of an individual, and it is also used to refer to the alleles present at one locus

Question 14

Define heritability

Answer 14

The degree to which a characteristic is determined by our genes

Question 15

Define heterozygote

Answer 15

This is an individual or genotype with two different alleles at a given locus on a pair of homologous chromosomes

Question 16

Define holoenzyme

Answer 16

The complete enzyme including all its subunits and cofactors

Question 17

Define homozygote

Answer 17

An individual or genotype with identical alleles at a given locus on a pair of homologous chromosomes

Question 18

Define hormone

Answer 18

A molecule produced by an endocrine cell, which is released into the blood stream and acts on specific receptors to elicit its effect

Question 19

Define host

Answer 19

The organism used to propagate a recombinant DNA molecule

Question 20

Define an insert

Answer 20

The fragment of foreign DNA cloned into a particular vector

Question 21

Define intron

Answer 21

A section of a gene that does not contain any instructions for making a protein

Question 22

Define karyotype

Answer 22

This is the chromosome complement of a cell

In a standard karyotype, the chromosomes are conventionally arranged in order depending upon size

Chromosomes are distinguished individually by their size, centromere position and banding pattern

The normal human karyotype is 46, XY (male) or 46, XX (female)

Question 23

Define library

Answer 23

A collection of cloned DNA fragments which, taken together, represent the entire genome of a specific organism

Using traditional techniques they allow the isolation and study of individual genes

Question 24

Define ligand

Answer 24

A molecule, such as a hormone or neurotransmitter, which binds to the receptor, and is termed the first messenger

Question 25

Define locus

Answer 25

The position of a gene on a chromosome

Question 26

Define microarray

Answer 26

A large set of cloned nucleic acid molecules or proteins spotted onto a solid matrix, usually a microscope slide, and used to profile gene and protein expression in cells and tissues

Question 27

Define monosomy

Answer 27

A chromosome constitution in which one member of a chromosome pair is missing

Question 28

Define multifactorial disorders

Answer 28

A term used to describe disorders in which both environmental and genetic factors are important

Question 29

Define mutation

Answer 29

A permanent heritable change in a sequence of DNA

Question 30

Define neurotransmitter

Answer 30

A molecule that is used to transmit nerve impulses across a synapse

Question 31

Define an operon

Answer 31

A prokaryotic locus, consisting of two or more genes that are transcribed as a unit and are expressed in a coordinated manner

Question 32

Define organism

Answer 32

An organism is a system capable of self-replication and self-repair, which may be unicellular or multicellular Unicellular organisms consist of a solitary cell able independently to perform all the functions of life Multicellular organisms contain several different cell types that are specialised to perform specific functions

Question 33

What is a pedigree chart?

Answer 33

They are used to illustrate inheritance

Question 34

Define penetrance

Answer 34

The proportion of individuals with a specific genotype that show the expected phenotype under defined environmental conditions The term is usually used in association with dominant disorders

Question 35

Define phenocopy

Answer 35

The alteration of the phenotype by environmental factors during development to produce a phenotype that is characteristically produced by a specific gene

Question 36

Define phenotype

Answer 36

The observed biochemical, physiological or morphological characteristics of an individual that are determined by the genotype and the environment in which it is expressed

Question 37

What is a plasmid?

Answer 37

Autonomously replicating, extrachromosomal circular DNA molecules Often exploited in the laboratory as a vector for gene cloning

Question 38

Define pleiotrophy

Answer 38

The phenomenon in which a gene is responsible for several distinct and apparently unrelated phenotypic effects, which may concern the organ system involved and the signs and symptoms that occur

Question 39

Define ploidy

Answer 39

This refers to the number of complete sets of chromosomes in a cell. A haploid cell contains a single set of chromosomes A diploid cell contains two copies of each chromosome A polyploid cell contains more than two sets of each chromosome

Question 40

What is polygenic inheritance?

Answer 40

This is a term used to describe the inheritance of traits that are influenced by many genes at different loci

Question 41

What is polymorphism?

Answer 41

Polymorphism is the occurrence in a population of two or more alternative genotypes, each at frequency greater than that which could be maintained by recurrent mutation alone A locus is arbitrarily considered to be polymorphic if the rarer allele has a frequency of at least 0.01 Any allele rarer than this is a 'rare variant'

Question 42

Define proband

Answer 42

The first person in a pedigree to be clinically identified as having a disease in question

Question 43

Define a probe

Answer 43

A probe is a radioactively or fluorescently labelled piece of single-stranded DNA of defined sequence

Question 44

Define recombinant DNA

Answer 44

A molecule of DNA created 'in vitro' that contains elements of more than one original sequence, e.g. vector and insert

Question 45

What is rolling circle replication?

Answer 45

A process of nucleic acid replication that can rapidly synthesise multiple copies of circular molecules of DNA such as bacterial chromosomes and plasmids

Question 46

Define translocation

Answer 46

The transfer of one segment of a chromosome to another

Question 47

Define trisomy

Answer 47

The state of having three representatives of a given chromosome instead of the usual pair (E.g. As in trisomy 21 - Down syndrome)

Question 48

What is variable expressivity?

Answer 48

This occurs when a genetic lesion produces a range of phenotypes: - e.g. tuberous sclerosis can be asymptotic with harmless kidney cysts, but in the next generation it may be fatal, owing to the development of brain malformations

Question 49

What is vector?

Answer 49

A DNA molecule capable of replicating within a particular host, into which foreign DNA may be inserted

Question 50

Define X-linked dominant

Answer 50

A trait (or a disease) that is produced when only one copy of a polymorphism or mutation is present on an X chromosome This means that both males and females can display the trait or disorder, by only having one copy of the gene

Question 51

Define X-linked recessive

Answer 51

A trait or disease that is produced when a polymorphism or mutation in a gene on the X chromosome causes the phenotype to be expressed