Download Double helix- a double twist

Topics on Genetics test –Tuesday 3/24
● DNA
o What is its shape?
Double helix- a double twist
o Who discovered the shape?
Watson & Crick (& Rosalind Franklin)
o DNA is the same in all of our cells (except sperm & egg, they have less DNA)
o What are the smaller building blocks?
Nucleotides
o What are the four bases? What is a base?
The 4 types of nucleotides. Bases are A,T,G,C
o Base-pair rules: A binds with T, C binds with G
o What does it do (its function)?
Contains genetic info. It is the hereditary information. The order of the bases
is important for directing all of your cells activities.
o Where is it found?
Nucleus
● Chromosomes
o Shape X shaped
o What are they?
X shaped structure that contains the DNA. DNA winds up into chromosomes
in order to keep it organized. If we stretched out A chromosome it is 3
meters long!
o Number of chromosomes in cells
46 total - We get 23 from mom & 23 from dad
o How many pairs?
23 pairs
o What are the 2 sex chromosomes?
X and Y
o What can happen if you have a wrong number of chromosomes?
Disease or death ( or nothing if you are lucky)
o What causes Down syndrome?
An extra 21st chromosome. Instead of 2 you have 3.
o What is a Karyotype? What does a Karyotype show?
A picture of all the chromosomes in the cell. Shows how many chromosomes you
have, if you are missing any or have extra. Can also see if it is a boy or a girl.
● Genes
o How is a Gene different from DNA?
A gene is a special section on the DNA that has the instructions to make a specific
protein. Each gene codes for one protein. The specific order of the bases tells your
cell what protein to make.
o What do genes code for?
Proteins
Environment
o We are made up of genes, but our ________________________________
effects our genes.
o Gene expression- genes are turned on and off in our different body cells. That is what
makes each cell different!
● The Human Genome Project- allowed scientists to know all the genes we have. How has this
helped people? Why is it important to know what genes we have- how has this changed medicine?
● Proteins
o What are proteins made of? (what is the smaller building block)
Amino acids
o In what organelle are proteins made?
The ribosome ( the little dots in the cell)
● Heredity
o What is heredity?
The transfer of traits (characteristics ) from parents to children (through the DNA).
o Why do we look like our parents (sometimes!)?
We get half our DNA from mom and half from Dad. Get a mixture of their genes
which code the same proteins and traits that they have.
o What do identical twins share?
DNA
● Mutations
o What is a mutation?
A mistake or change in the DNA. Instead of a G there might be a T. Not
good!
o Where do mutations occur?
In the DNA. If it's in our genes (the important sections) that's very bad
o What is a genetic disorder?
When a mutation in our genes causes disease
● Cancer
o What is cancer?
When our cells reproduce like crazy and can't stop making more cells.
Uncontrolled cell growth.
o What is a tumor?
A ball of cancer cells
o What causes cancer?
Mutations in the DNA
o What things in the environment can cause cancer?
X-Rays. The sun. Chemicals.
● Selective breeding
o What is it?
When we breed animals that have the best traits so we get animals that
look how we want.
o Know a few common examples.
Dogs!!!!