Question

in normal hair, specific proteins combine with a substance called keratin to give the hair shaft its shape and structure. together, they give the hair shaft strength and stability. these proteins are formed by three different genes.

1. which event created the genetic change that causes uncombable hair syndrome (uhs)?

a. crossing over during mitosis
b. a mutation in a gene that codes for hair - shaft proteins
c. a mistake in protein folding caused by brushing hair
d. environmental heat damage to hair

1. drag the following steps into the correct order to show how a mutation leads to a new trait.

a. protein produced has a different structure
b. dna sequence changes in a gene
c. hair shaft forms with altered shape

1. which macromolecule directly determines the structure of hair - shaft proteins?

a. dna
b. lipids
c. carbohydrates
d. nucleotides only in rna

1. proteins in hair shafts are made of:

a. amino acids
b. simple sugars
c. fatty acids
d. nitrogen bases

1. the strength and stability of normal hair shafts are mainly due to:

a. dna molecules inside each hair
b. proteins that combine with keratin
c. sugars stored in hair follicles
d. lipid layers around the hair shaft

1. why does a mutation in dna change a hair trait?

a. dna carries energy for hair growth
b. carbohydrates in dna provide color
c. proteins are coded by dna, and protein structure affects hair shape
d. lipids block gene expression

1. which molecule carries the instructions from dna to the ribosome to build hair - shaft proteins?

a. trna
b. mrna
c. keratin
d. ribosome rna only

Explanation:

1. DNA contains the genetic information that codes for proteins. Proteins are made of amino acids. The strength and stability of hair shafts come from proteins combining with keratin.
2. A mutation in a gene (which is part of DNA) that codes for hair - shaft proteins can cause Uncombable Hair Syndrome.
3. For the process of mutation leading to a new trait: first, the DNA sequence changes in a gene (b), then the protein produced has a different structure (a), and finally, the hair shaft forms with an altered shape (c).
4. DNA codes for proteins, and protein structure affects hair shape. mRNA carries the instructions from DNA to the ribosome.

Answer:

1. a. DNA
2. a. Amino acids
3. b. Proteins that combine with keratin
4. b. A mutation in a gene that codes for hair - shaft proteins
5. b, a, c
6. C. Proteins are coded by DNA, and protein structure affects hair shape
7. b. mRNA