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Course: Middle school biology - NGSS > Unit 7
Lesson 5: Reproduction and genetic variation- Sexual reproduction and genetic variation
- Sexual reproduction and genetic variation
- Genetics vocabulary
- Worked examples: Punnett squares
- Genetics vocabulary and Punnett squares
- Understand: sexual reproduction and genetic variation
- Apply: genetics vocabulary
- Apply: Punnett squares
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Genetics vocabulary and Punnett squares
Review your understanding of genetics vocabulary and Punnett squares in this free article aligned to NGSS standards.
Key points:
- An organism’s traits are affected by its genes. Genes can have variations, called alleles. Different alleles of a gene can cause different versions of a trait.
- Many organisms have two alleles for each gene. One allele is inherited from each parent. An organism’s combination of alleles is called its genotype.
- Genotypes can be homozygous or heterozygous for a gene. A homozygous genotype has two of the same alleles. A heterozygous genotype has two different alleles.
- A phenotype is an observable version of a trait.
- An organism’s phenotype is the result of its combination of alleles. Alleles can be dominant or recessive. Dominant and recessive alleles affect an organism’s phenotype in different ways.
- A dominant allele determines the phenotype, even if the genotype also contains a recessive allele. A dominant allele is usually shown as an uppercase letter.
- A recessive allele only determines the phenotype if there is no dominant allele present. A recessive allele is usually shown as a lowercase letter.
- A Punnett square is a model that represents a cross, or breeding event, between two organisms. A Punnett square helps predict the likelihood of certain offspring genotypes and phenotypes, given the genotypes of two parents.
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Based off the image I conclude that Khan Academy dislikes yellow peas.(32 votes)
what happens when there is two dominant alleles?(7 votes)
Both will be expressed; both will blend.
The blending will also happen with two recessive alleles.(6 votes)
but how do we explain this to Fortnite kids?(6 votes)
so when renegade raider and Spiderman met they exchange light ammo and then renegade raider poops out little renegade raider(5 votes)
An organism’s traits are affected by its genes. Genes can have variations, called alleles. Different alleles of a gene can cause different versions of a trait.
Many organisms have two alleles for each gene. One allele is inherited from each parent. An organism’s combination of alleles is called its genotype.
Genotypes can be homozygous or heterozygous for a gene. A homozygous genotype has two of the same alleles. A heterozygous genotype has two different alleles.
A phenotype is an observable version of a trait.
An organism’s phenotype is the result of its combination of alleles. Alleles can be dominant or recessive. Dominant and recessive alleles affect an organism’s phenotype in different ways.
A dominant allele determines the phenotype, even if the genotype also contains a recessive allele. A dominant allele is usually shown as an uppercase letter.
A recessive allele only determines the phenotype if there is no dominant allele present. A recessive allele is usually shown as a lowercase letter.
A Punnett square is a model that represents a cross, or breeding event, between two organisms. A Punnett square helps predict the likelihood of certain offspring genotypes and phenotypes, given the genotypes of two parents.(7 votes)
How do I memorize this?(7 votes)- how do i read this(4 votes)
- you know, every human have eyes, you can use them, but if you are blind, ask a friend to read it to you(6 votes)
what does genetic code mean?(2 votes)
Genetic codes are the 'instructions' that tell our cells how to reproduce.(4 votes)
- If there were no genotypes or phenotypes,would there be no children?(3 votes)
If there were no genotypes or phenotypes, there would not be children because the genotypes is the genetic makeup of an offspring(or kid), and the phenotype is the physical makeup of the offspring. Both rely on each other. It depends on the genotype if the kid is going to be tall or not, and it depends on the phenotype on how they show the genotype. So if none were present, then the children would not exist. Hope this helped! :)(1 vote)
how do you get that?(3 votes)- what happens when there is two dominant alleles?(3 votes)
- 2 dominant alleles just show the dominant. Here is an example: Brown is dominant. Blue is not. If there are 2 browns combined, the eye is brown. If there is 1 of each, the dominant will determine the color, in our case, brown. If there are 2 blues, then the eye is blue.(1 vote)