The language of genetics
Introduced| English | Meaning |
|---|---|
| locus/ˈləʊkəs/ | The particular position of a gene or DNA sequence on a chromosome. |
| dominant/ˈdɒmɪnənt/ | Describing an allele whose effect is expressed in a heterozygote. |
| recessive/rɪˈsesɪv/ | Describing an allele whose effect is masked by a dominant allele in a heterozygote. |
| codominant/ˈkəʊdəmɪnənt/ | Describing alleles whose effects are both expressed in a heterozygote. |
| genotype/ˈdʒenətaɪp/ | The genetic constitution of an organism, or the alleles it has at specified loci. |
| phenotype/ˈfenətaɪp/ | The observable characteristics of an organism, resulting from its genotype and environmental influences. |
| homozygous/ˌhɒməˈzɪɡəs/ | The two alleles are the same. |
| heterozygous/ˌhetrəˈzɪɡəs/ | Having two different alleles at a particular gene locus. |
| test cross/test krɒs/ | A cross between an individual of unknown genotype and a homozygous recessive individual to help determine the unknown genotype. |
Speaking the genetic language
- Genetics has precise terms you must use exactly.
- Get these right and every cross becomes easy.
- Let's build them up in groups.
Genetics vocabulary lab
Link each genetics word to the real feature it names.
Genes and alleles
- a gene is a length of DNA that codes for a protein; its position is its locus 基因座.
- an allele is one version of a gene.
- a dominant 显性 allele shows its effect with only one copy; a recessive 隐性 allele needs two copies.
- codominant 共显性 alleles both show together.
An allele is:
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An allele is a version of a gene; its position on the chromosome is the locus.
A recessive allele:
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A recessive allele is only expressed when homozygous; a dominant allele shows with a single copy.
Match each genetics term to its meaning.
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Genotype is the alleles you carry; phenotype is what shows; an allele is a version of a gene at its locus.
Genotype 基因型 and phenotype 表现型
- the genotype is the alleles an organism has.
- the phenotype is the features you can see.
- homozygous 纯合 = the two alleles are the same; heterozygous 杂合 = they are different.
The observable features of an organism (what you can actually see) are its ______.
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Phenotype = what shows; genotype = the alleles present (which, with the environment, decide the phenotype).
An organism that carries two different alleles of a gene is homozygous.
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False. Two different alleles make it heterozygous; homozygous means two identical alleles.
The test cross 测交
- A test cross finds an unknown genotype.
- You cross the organism with the recessive homozygote.
- The offspring reveal whether the unknown was homozygous or heterozygous.
A test cross finds an unknown genotype by crossing it with:
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Crossing with the recessive homozygote reveals whether the unknown carries a recessive allele.
You've got it
- gene (codes a protein) at a locus; an allele is a version of it
- dominant shows with one copy; recessive needs two; codominant both show
- genotype = alleles you have; phenotype = features you see
- homozygous (same) vs heterozygous (different); test cross with the recessive homozygote finds an unknown genotype
Write from two different alleles
- A person has one allele for a dominant character and one for the recessive character.
- Both alleles are of the same gene.
What word describes this genotype?
Different alleles of one gene make a heterozygote.
What is a genotype with two different alleles called?
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Hetero means the two alleles differ.