Biology Definitions

Question 0

Genotype

Answer 0

A statement of the genes a person has for a characteristic

Question 1

Phenotype

Answer 1

A statement of the physical appearance of the person for that characteristic

Question 2

Homozygous

Answer 2

Where both of the chromosomes carry the same allele e.g. TT or tt

Question 3

Heterozygous

Answer 3

Where the chromosomes each carry a different alleles for that characteristic e.g. Tt

Question 4

Autosomal

Answer 4

Not sex linked. Genes on chromosomes that don’t determine sex ie. same for males and females

Question 5

X – linked

Answer 5

Sex linked. Genes that change depending on the sex of the organism. They are found on the X and Y chromosome’s

Question 6

Gene

Answer 6

The basic functional unit of a DNA molecule that contributes to the inheritance of characteristics

Question 7

Chromosome

Answer 7

A strand of DNA and associated proteins. It contains genes at different loci.

Question 8

Loci

Answer 8

The position of a gene on a chromosome

Question 9

Allele

Answer 9

The alternative forms of genes that occupy the same locus on homologous chromosomes. They are expressed as different forms of the same characteristic.

Question 10

Homologous chromosome

Answer 10

Members of a pair of chromosomes of similar structure, containing genes at the same loci, which pair during meiosis

Question 11

Haploid

Answer 11

The number of chromosomes found in a gamete (n). This is half the number found in an ordinary body cell. Haploid cells are found in the ovary and testes. (Humans = 23)

Question 12

Diploid

Answer 12

The number of chromosomes found in an ordinary body cell (or somatic cell). Found all over body.

Question 13

Dominance

Answer 13

If one gene masks the effect of another. It is written with a capital letter

Question 14

Recessive

Answer 14

A gene that is masked. It is written with a lowercase letter.

Question 15

Crossing over

Answer 15

Crossing over will occur between the two in a chromatids of a pair of homologous chromosomes during meiosis and allows an exchange of genetic material from the mother and father.

Question 16

Mutation

Answer 16

A spontaneous, random change to a gene, many genes or a whole chromosome. If the mutation is in a somatic (normal) body cell, it will affect the organism but not be passed on but if it is in a sex cell it will be inherited by the offspring.

Question 17

Recombinant DNA

Answer 17

rDNA or recombinant DNA is a form of artificial DNA that is created by combining two or more sequences that would not normally occur. E.g. bacteria that makes insulin, BT cotton, hep B

Question 18

DNA

Answer 18

Deoxyribonucleic acid

Double-stranded helix, located in nucleus, chloroplasts and mitochondria.

Nucleosome (wrapped DNA) histone complex

Cell division – chromatin condenses into chromosomes so DNA can be transported to daughter cells

Arrangement in prokaryote’s – in circular ring, not coiled, also have smaller rings of DNA called plasmids

Question 19

Prokaryote’s

Answer 19

Single celled organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelles.

Question 20

Eukaryote

Answer 20

Membrane bound organelles

Question 21

Natural selection

Answer 21

The mechanism by which evolutionary change on earth has occurred.

Question 22

Mutations

Answer 22

A sudden, permanent change in a gene (gene mutation) many genes or a whole chromosome (chromosome mutation) and may introduce variation into the population.

Question 23

Somatic mutation

Answer 23

Occurs in a somatic (normal) body cell. It will affect the organism but not the offspring. E.g. not passed on.

Question 24

Sex Cell mutation

Answer 24

Occurs in sex cells. It will affect the offspring e.g. passed on/inheritable trait.

Question 25

Competition

Answer 25

Life is an ongoing struggle for survival so organisms compete for food, water, mates, sunlight, space and other resources in order to survive. If they cannot compete successfully then their chance of survival is slim and they won't pass on their genes to future generations.

Question 26

Survival of the fittest

Answer 26

"Fitness" (the reproductive success and survival of individuals within species) Within species variation exist and since resources are limited, competition also exist. Individuals who compete successfully for resources are more likely to pass on the favourable characteristics to the offspring.

Question 27

"Fitness"

Answer 27

the reproductive success and survival of individuals within species

Question 28

Adaptation

Answer 28

Characteristics which best suit an organism to their environment. Those with favourable adaptations pass on genetics to the next generation, those with unfavourable characteristics will die and not pass on genes so the next generation will be better adapted.

Question 29

Selective pressures

Answer 29

Environmental factors which may reduce reproductive success in a population therefore contribute to ebullition airy change for extinction through the process of natural selection. E.g. competition, predation, disease, parasitism, land clearance, climate change, pollutants

Question 30

DNA profiling

Answer 30

Where are specific DNA pattern, called a profile, is obtained from the person or sample of bodily tissue. A process that is able to identify natural variations that exist within an individual's genome, by using the polymerase chain reaction and gel electrophoresis.

Question 31

Polymorphic

Answer 31

Pieces of DNA that very highly between individuals of the same species

Question 32

Polymorphisms

Answer 32

Differences in variable regions of DNA

Question 33

Short tandem repeats (STR's)

Answer 33

A type of polymorphism. A region of non-coding DNA that contains repeats of the same nucleotide sequences. STR's are found at different places/genetic loci in a person's DNA.

Question 34

Transgenic organism

Answer 34

One whose genome has been altered by adding genes from a different species into it's genome using recombinant DNA technology.

Question 35

Genetically modified organism

Answer 35

One whose genome has been modified or altered by gene manipulation and biotechnology, in particular recombinant DNA technology, to give it characteristics it does not have naturally.

Question 36

Codon

Answer 36

Series of three adjacent nucleotide bases in messenger RNA; each codon specifies a particular amino acid to be added to a polypeptide; stop codon indicates the termination of the polypeptide chain.

Question 37

DNA ligase

Answer 37

An enzyme used to catalyse the formation of a bond between two pieces of DNA.

Question 38

DNA polymerase

Answer 38

An enzyme capable of making exact copies of fragments of DNA

Question 39

DNA sequencing

Answer 39

A process of establishing the nucleotide sequence of a piece of DNA

Question 40

DNA Helicase

Answer 40

An enzyme that helps the two strands of the DNA double helix unwind and separate

Question 41

DNA fingerprinting

Answer 41

Also called DNA profiling; based on patterns of non-coding, repeating bass sequences in the genome.

Question 42

Genetic code

Answer 42

The system by which each combination of three DNA nucleotides in a gene sequence determines specific amino acid in a protein.