DNA and Genetics - Chapter 4

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

Genes, alleles, loci and chromosomes

A gene encodes a protein. These proteins will result in having certain (hereditary) traits. 

Every gene is located on a fixed spot on the genome. This spot is called a locus (pleural: loci).

Each gene might have different variants. A gene variant is called an allele.

Because a diploid organism has two copies of each chromosome (homologous), this organism will have two loci of each genes. These may carry the same or different alleles. 

01:20

What is the differences between a dominant and a recessive allele?

02:07

How do we call a genotype with 2x the same allele?

Black fur(B) in guinea pigs is dominant over white fur(b). Find the probability of heterozygous offspring in the cross: BB x Bb.

Black fur(B) in guinea pigs is dominant over white fur(b). Find the probability of a white offspring in a cross: Bb x bb

A chicken with white feathers is crossed with a rooster with black feathers. The gray offspring in F1 are crossbred.

Which phenotypes are found in the F2?

A woman with blue eyes has a child with brown eyes. The allele for B brown eyes is dominant over the allele for B blue eyes. What genotype (s) could the father have had?

In cats, the gene for a spotted coat (R) is dominant over that for an unspotted coat (r). A female with spotted fur gives birth to a male with spotted fur. Among the young are animals with a spotted coat and animals with an unspotted coat. What are the genotypes of the parent animals?

What are the genotypes of these heterozygous guinea pigs?

What percentage is Hh?

1. 25%
2. 50%
3. 75%

What percentage of these guinea pigs have hair?

1. 25%
2. 50%
3. 75%
4. 100%

1. A heterozygous dog with a dominant black fur (B) reproduces with a homozygous dog with white fur. What is the genotype of the white dog?

3. A heterozygous dog with a dominant black fur (B) reproduces with a homozygous dog with white fur. What are the genotype percentages?

2. A heterozygous dog with a dominant black fur (B) reproduces with a homozygous dog with white fur. What are the sex cells going to be?

What is the genotypic ratio?

Two parents are heterozygous for brown eyecolor. What is the chance of getting a child with blue eyes?

1. 0%
2. 25%
3. 50%
4. 100%

What are the phenotypic percentages of the offspring?

Jule's and jacob's dad has blue eyes. Mom has brown eyes. Jule herself has blue eyes. How high is the chance for Jacob having brown eyes?

1. 0%
2. 25%
3. 50%
4. 100%

Stambomen

Pedigrees (Family trees)  

• Show how certain traits are inherited
• Circle: woman
  
• Square: man
  

Write down the genotypes of the guinea pigs (white fur = recessive)