Structure and Function of DNA
DNA has the shape of a ...
Double Helix
Describe the function/purpose of DNA in organisms. What is a gene?
To store the information needed for all cell functions. DNA acts as the blueprint for life.
A gene is a sequence of DNA nucleotides that acts as a recipe for a specific protein.
A single stranded piece of a DNA has the following bases: ACTGAG. What is the matching sequence on its RNA transcript (the mRNA)?
UGACUC
What is a protein? What determines it's function?
a molecule that is made up of amino acids and express various traits.
Because each amino acid has specific chemical characteristics, the sequence of amino acids determines the structure and shape of a protein.
What is a mutation? Name 2 environmental factors can cause a mutation.
Any change to an organism's DNA/genome. Environmental factors: chemicals, radiation, sun, food, & viruses
One DNA strand has a base sequence GTCCATA. The base sequence on the second strand of DNA is...
CAGGTAT
What is the end product of DNA replication (be very specific!)
Two new molecules of DNA, each is identical to each other and to the original molecule.
Transcription: What does is make? Where does it take place?
mRNA code for building proteins Nucleus.
What cell organelle makes protein? What are the monomers or building blocks of protein called? What is this process called?
Ribosome / amino acids/ translation
Are all mutations harmful? If not, give a counter example.
Helpful mutations: having ONE sickle cell gene makes you immune to the parasite that causes malaria. Neutral mutations: blue eyes
What do we call the monomers or building blocks of DNA?
What are its 3 parts?
Which two parts form the backbone?
What is the function of the backbone?
Nucleotide:
phosphate group, sugar (deoxyribose), base (A, C, T, or G).
The phosphate and sugar form the backbone. The backbone provides structure and support for the molecule.
Order these terms by size from largest to smallest:
Nucleotide, cell, gene, chromosome.
cell, chromosome, gene, nucleotide
cells contain chromosomes
Each chromosome has one long molecule of DNA
A gene is a section of this DNA molecule
Nucleotides are the pieces that make up the DNA molecule
Why can’t DNA leave the nucleus?
DNA is too long/bulky to exit through the nuclear pores.
What is an anti-codon? What is its purpose?
A 3 nucleotide sequence on a tRNA that matches to a specific mRNA codon. When a tRNA finds a matching mRNA codon (with the ribosomes help), it drops off the attached amino acid to be used in protein.
What is a variation and how does it affect an organism?
differences in a genetic sequence that results in different traits among a species.
Variations in the DNA code of a gene can change either the structure of a protein or when and where it is produced. If these variations change the protein structure, they could also change its function.
These two men are credited with figuring out the shape & structure of DNA. They used a photograph taken by a female fellow scientist.
James Watson and Francis Crick Rosalind Franklin
Why does DNA need to be copied?
So that when the cell divides, each new cell has a complete set of DNA.
Name the three different types of RNA and describe the function of each of them.
mRNA: delivers a copy version of a DNA gene from the nucleus to the ribosome. tRNA: transfers the amino acids to the ribosome. rRNA: part of the ribosome.
Describe the relationship between DNA, genes, proteins, and traits.
genes code for proteins, not traits. genes affect these traits indirectly by way of the proteins created via DNA.
DNA carries information in the sequence of base pairs of its nucleotides.
The types and sequence of nucleotides in DNA determine the types and sequence of nucleotides in RNA. This in turn determines the types and order of amino acids included in proteins.
Describe how a mutation could result in a breed of dog with curly hair instead of straight.
There is a change in the order, number, or types of nucleotides that code for hair type. This variation results in different codons and different amino acids which build a different protein with a different structure and shape that results in curly hair on the dog instead of straight.
In a sample of DNA, 40% of the bases are adenine. What percentage of bases are guanine?
10%
How does DNA replication take place?
1. UNWIND unzips/unwinds the DNA helix by breaking the bonds between the bases.
2. REPLICATE DNA polymerase: makes DNA by adding complementary bases to the other side of each of the original strands.
3. REWIND Strands form new hydrogen bonds between the bases creating two strands from the one.
Name 4 differences between DNA and RNA.
DNA: deoxyribose, thymine, long, double-stranded, made by DNA replication.
RNA: ribose, uracil, short, single-stranded, made by transcription.
Challenge!
This is what we call a chain of amino acids (a protein before it gets its shape)
Polypeptide.
Challenge:
What is a frameshift mutation?
This type of mutation occurs when bases are inserted or deleted, causing ALL the codons from the point of mutation forward to change, thus change causing all the amino acids to change.