Topic 3 (Genetics) -- PART 2 Flashcards
(18 cards)
What is a gene vs an allele?
A gene is a portion of DNA that determines a certain trait whereas an allele tells us the variation in which a given trait can be expressed.
for ex:
gene –> codes for eye color
allele –> tells us whether the eye color is blue or brown
Where are genes located?
genes are location on specific sections of the chromosome
What does DNA stand for?
Deoxyribonucleic acid
What is the shape of DNA?
double helix – shaped like a twisted ladder
Where is DNA found in the cell?
within the nucleus
What is the structure of DNA?
DNA is made up of millions of NUCLEOTIDES bonded together in a double helix structure
what is a nucleotide?
Phospate + 5-carbon sugar + NUCLEOBASE
what are the nucleobase?
Adenine (A), Thymine (T), Guanine (G), Cytosine (C)
what are the pairs of nucleobases that we ALWAYS see in DNA
Adenine —— Thymine
Thymine —– Adenine
Cytosine —– Guanine
Guanine —– Cytosine
If I have this strand of DNA
AATCGC
I I I I I I
_ _ _ _ _ _
What would the matching strand look like?
TTAGCG
If I have this strand of DNA
TCGATCGGGCATTTTCAG
What would the matching strand look like?
AGCTAGCCCGTAAAAGTC
Why is DNA twisted into a double helix?
it takes up less space and protects the 3 billion nucleobases found in DNA
what is a mutation?
change in the genetic sequence of DNA
are mutations always harmful?
NO in some cases mutations do not harm the natural processes in the body
for example, mutation allows humans to digest LACTOSE as adults –> lactose persistence
how do you know whether a mutation will be transferred to offspring?
if the mutation is located on a gamete (reproductive cells) –> mutation has a chance to be inherited by the offspring
if the mutation is located on a body cell (for ex hair cell, eye cell, skin cell, stomach cell) –> the offspring will not inherit that mutation
how do mutations occur?
they can occur naturally, or via mutagenic agents, or by the environment
what is a mutagenic agent? give examples
something that makes it easier for DNA to become mutated
for ex, x-rays, radiation, UV light, radioactive susbtances
how do the himalayan white rabbits show how environment affects gene expression
himalayan rabbits live in the snow. their fur production is dependent on the temperature of the environment. cooler temperature results in dark fur whereas hotter temperature results in white fut. the rabbits tail, paws, nose, and ears are usually touching cold air or snow so they are brown. the rest of the rabbit is white because it is not exposed to cold areas as much as the tail, paws, nose, and ear
