Download 1a.Genetics Key Terms

Genetics Key Terms
Match the following terms with their definitions by writing the corresponding number of a term in the box with
its definition.
Terms
Definitions
1. Allele for the
dominant trait
A specific sequence of DNA that codes for a particular trait (e.g. eye colour)
2. Allele for the
recessive trait
Having two copies of the same allele (e.g. AA or aa)
3. Gregor Mendel
Having one set of chromosomes
4. Chromosome
A diagram used to predict the results of reproduction between different
organisms
5. Gene
Cell division in which one cell divides to produce daughter cells with half the
number of chromosomes as the original cell
6. Karyotype
Characteristics that are not clearly defined e.g. height)
7. Haploid
A structure that makes up proteins. One codon will help produce one amino
acid.
8. Diploid
A diagram showing all the different chromosomes we have
9. Mitosis
Manipulating DNA to change the genes within an organism
10. Meiosis
The process of DNA copying itself. First the double helix must unwind, the two
strands ‘unzip’ and complementary bases are added to the two strands to create
two new strands.
11. Allele
The process of identifying individuals based on their DNA. It can be used to
determine the parents of a child or help solve criminal cases.
12. Homozygous or purebreeding
A small piece of DNA with a sequence of bases identical to a piece of DNA that
we want to examine. This probe can be used to extract the DNA of interest.
13. Heterozygous or
hybrid
Different forms of the same gene (e.g. you may have one for blue eyes and one
for brown eyes)
14. Genotype
Organisms whose genes have been changed artificially
15. Phenotype
When a trait is carried on an X or Y chromosome
16. Punnett Square
The combination of genes an individual has (e.g. Bb)
17. Co-dominance
A ‘map’ of all the genetic material in humans
18. Incomplete
dominance
The phenotype of an offspring is a combination of the phenotypes of the
heterozygous organisms – i.e. the offspring shows both characteristics for a
particular trait. For example, a pure red cow (RR) is crossed with a pure white
cow (WW), producing a ‘roan’ cow (RW) which is both red and white.
19. Continuous variation
A diagram used to trace the inheritance of traits through a family.
20. Discontinuous
The allele that is masked by the dominant allele. An individual needs two copies
variation
of this allele for it to be expressed (seen in the phenotype)
21. Pedigree
Removing some DNA or genes from an individual, changing it, and putting it back
in the same person.
22. Sex-linked inheritance
Having two sets of chromosomes
23. DNA
Purposely breeding organisms that have favourable traits
24. DNA replication
The physical characteristics of an individual (e.g. brown hair)
25. Codon
Producing an organism from a single cell. One body cell is taken from an
organism and used to produce a new individual.
26. Amino acid
An agent that increases the risk of mutation (e.g. radiation)
27. Gene expression
The heterozygous offspring has a phenotype that is a mixture between the
phenotypes of the two homozygous organisms. For example, a red snapdragon
(R1R1) crossed with a white snapdragon (R2R2) produces a pink snapdragon (R1R2)
28. Mutation
A set of three nitrogenous bases
29. Mutagen
The allele that masks the effect of the recessive allele. An individual only needs
one copy of this allele for it to be expressed (see in the phenotype)
30. Selective breeding
An organism that has had a new gene inserted into their DNA
31. Genetic engineering
Cell division in which one cell divides to produce two identical daughter cells
32. Genetically modified
A spontaneous change in a gene or chromosome
33. Transgenic
Having two different alleles (e.g.Aa)
34. Gene probe
The appearance of characteristics in an organism that are coded for by genes
35. DNA fingerprinting
Characteristics that are clearly defined. For example, you are either left-handed,
right-handed or ambidextrous. You are either albino or not.
36. Cloning
Structures within the nucleus of cells that are made up of DNA
37. Gene therapy
A chemical that makes up chromosomes and determines the particular traits we
have (i.e. what we look like)
38. Human genome
The ‘father’ of genetics. His experiments on pea plants are responsible for much
of our knowledge of genetics.
Genetics Key Terms: Answers
Terms
Definitions
1. Allele for the
dominant trait
The allele that masks the effect of the recessive allele. An individual only needs
one copy of this allele for it to be expressed (see in the phenotype)
2. Allele for the
recessive trait
The allele that is masked by the dominant allele. An individual needs two copies
of this allele for it to be expressed (seen in the phenotype)
3. Gregor Mendel
The ‘father’ of genetics. His experiments on pea plants are responsible for much
of our knowledge of genetics.
4. Chromosome
5. Gene
6. Karyotype
Structures within the nucleus of cells that are made up of DNA
A specific sequence of DNA that codes for a particular trait (e.g. eye colour)
A diagram showing all the different chromosomes we have
7. Haploid
Having one set of chromosomes
8. Diploid
Having two sets of chromosomes
9. Mitosis
Cell division in which one cell divides to produce two identical daughter cells
10. Meiosis
Cell division in which one cell divides to produce daughter cells with half the
number of chromosomes as the original cell
11. Allele
12. Homozygous or purebreeding
13. Heterozygous or
hybrid
Different forms of the same gene (e.g. you may have one for blue eyes and one
for brown eyes)
Having two copies of the same allele (e.g. AA or aa)
Having two different alleles (e.g.Aa)
14. Genotype
The combination of genes an individual has (e.g. Bb)
15. Phenotype
The physical characteristics of an individual (e.g. brown hair)
16. Punnett Square
A diagram used to predict the results of reproduction between different
organisms
17. Co-dominance
The phenotype of an offspring is a combination of the phenotypes of the
heterozygous organisms – i.e. the offspring shows both characteristics for a
particular trait. For example, a pure red cow (RR) is crossed with a pure white
cow (WW), producing a ‘roan’ cow (RW) which is both red and white.
18. Incomplete
dominance
19. Continuous variation
20. Discontinuous
variation
21. Pedigree
The heterozygous offspring has a phenotype that is a mixture between the
phenotypes of the two homozygous organisms. For example, a red snapdragon
(R1R1) crossed with a white snapdragon (R2R2) produces a pink snapdragon (R1R2)
Characteristics that are not clearly defined e.g. height)
Characteristics that are clearly defined. For example, you are either left-handed,
right-handed or ambidextrous. You are either albino or not.
A diagram used to trace the inheritance of traits through a family.
22. Sex-linked inheritance
When a trait is carried on an X or Y chromosome
23. DNA
A chemical that makes up chromosomes and determines the particular traits we
have (i.e. what we look like)
24. DNA replication
The process of DNA copying itself. First the double helix must unwind, the two
strands ‘unzip’ and complementary bases are added to the two strands to create
two new strands.
25. Codon
A set of three nitrogenous bases
26. Amino acid
A structure that makes up proteins. One codon will help produce one amino
acid.
27. Gene expression
The appearance of characteristics in an organism that are coded for by genes
28. Mutation
A spontaneous change in a gene or chromosome
29. Mutagen
An agent that increases the risk of mutation (e.g. radiation)
30. Selective breeding
Purposely breeding organisms that have favourable traits
31. Genetic engineering
Manipulating DNA to change the genes within an organism
32. Genetically modified
Organisms whose genes have been changed artificially
33. Transgenic
An organism that has had a new gene inserted into their DNA
34. Gene probe
A small piece of DNA with a sequence of bases identical to a piece of DNA that
we want to examine. This probe can be used to extract the DNA of interest.
35. DNA fingerprinting
36. Cloning
37. Gene therapy
38. Human genome
The process of identifying individuals based on their DNA. It can be used to
determine the parents of a child or help solve criminal cases.
Producing an organism from a single cell. One body cell is taken from an
organism and used to produce a new individual.
Removing some DNA or genes from an individual, changing it, and putting it back
in the same person.
A ‘map’ of all the genetic material in humans