DNA/GENETICS

What are the three parts of a DNA nucleotide?

Phosphate group, nitrogenous base, pentose sugar

What does a double helix look like and why is DNA shaped that way?

It has two intertwined strands of DNA with rungs made of paired nitrogenous bases. It it shaped that way due to the phosphate backbone.

What can you learn from a karyotype?

It shows the shape and the number of chromosomes and if there are any abnormalities. Example = Turner syndrome, missing or damaged X chromsome

Name one genetic disorder and what causes it

Trisomy 21 - There are three copies of the 21st chromosome

What is an allele? Give an example.

Different versions of a gene for the same trait. For example, blue and brown eyes.

Genotype vs Phenotype

Genotype is the genetic makeup of an organism while phenotype is the physical trait expressed. For example the genotype is BB and the phenotype is brown eyes.

What makes a sex linked trait? Give an example

Traits controlled by genes on the X chromosome. For example, colorblindness.

What is the base pairing rule and why is it important?

Adenine always pairs with thymine and guanine always pairs with cytosine. These rules are essential for correct DNA replication.

Why are hydrogen bonds important in DNA structure and replication?

Hydrogen bonds holds the DNA double helix strand together and allow for pairing of the nitrogenous bases. Make it easy for the strands to separate during replication.

What enzyme unzips DNA during replication?

DNA helicase. It breaks the bonds between the nucleotides.

What enzyme builds the new DNA strand?

DNA polymerase. Adds nucleotides to the growing strand.

What is a mutation? How can it affect proteins?

A mutation is a change in the DNA sequence of an organism. This can affect the proteins structure or function. For example, a missense mutation changes one amino acid into another.

How can the environment affect your phenotype?

Factors such as diet (growth and development), stress (health and behavior), and temperature (heat exposure = increased melanin production), can affect your genotype by altering gene expression.