Biology DNA and RNA exam

DNA are macromolecules called ______. They are made up of smaller, monomer units called _____.

Nucleic acids, nucleotides

Structure of a nucleotide

The structure and function of DNA

2 strands, double helix shape, deoxyribose sugar, adenine, thymine, cytosine or guanine bases, made for storing genetic info copying info and gene expression.

The structure of RNA

1 strand, single strand shape, ribose sugar, adenine, uracil, cytosine or guanine bases, made for converting DNA’s genetic information into proteins

Where is genetic information in DNA carried?

Order of the bases

What are there always equal amounts of? (Chargaff’s rule)

A & T, C & G

If a sample of DNA has 20% T, what percentage of A, C, and G does it have?

20% A 30% C 30% G

What is the arrangement of two strands of DNA in opposite directions?

Antiparallel

Explain the experiment by Hershey and Chade that proved DNA was hereditary material

Tested what part of a bacteriophage virus carried genetic info of bacteria. Grew viruses using Phosphorus-32 or Sulfur-35, let viruses infect bacteria, nearly all p-32 was in the bacteria

What is replication?

Process of copying DNA

Each new DNA helix is made up of one original or _____ strand, and one new or _____ strand. DNA replication is said to be __________ because each new helix has a half of the original DNA.

Leading, lagging, semi-conservative

What is meant by complementary base pairing?

If you know the order of one, you know the order of the other

What is the advantage of complementary base pairing in replication?

Makes duplication simple, copying is more accurate

First step of replication

Original DNA molecule unzips between the nitrogen bases and the strands separate.

Second step of replication

The enzyme DNA polymerase bonds the two new nucleotides together.

Third step of replication

The new DNA is proofread for any errors

When RNA is formed alongside DNA, the _____ in RNA bonds with adenine in the DNA strand.

Uracil

The ____ on the RNA strand will bond with the thymine in the DNA

adenine

First step of transcription

The enzyme RNA polymerase attaches to the promotor, which indicates where replication should start. DNA nucleotides separate.

Second step of transcription

RNA polymerase joins the RNA nucleotides together to form RNA

Third step of transcription

RNA polymerase comes to a termination sequence. The new RNA leaves the nucleus, the DNA bonds together again.

DNA → RNA → Protein

Any changes in the _____ can cause changes in the final ______

DNA, protein

The “Central dogma” is called such because all life on Earth shares the same five nucleotide bases:

Adenine, cytosine, thymine, uracil, and guanine

mRNA structure and function

Single stranded complementary copy of DNA’s instructions to make a protein. Each 3 bases are a codon a code that specifies a specific amino acid.

rRNA structure and function

2 RNA subunits and some proteins. The RNA strands fold to form a ball-like structure. Attaches to a strand of mRNA and directs the production of the new proteins.

tRNA structure and function

folded into a t-shape, carrying amino acid on the end, has a 3-case anticodon. Carries amino acids into correct position by temporarily bonding it’s anticodon to the mRNA codon.

mRNA is a sequence of 3 base words, or ____. There is a total of ___ possible codons, and only ___ types of amino acids.There are also start and ___ codons.

Codons, 64, 20, stop

First step of translation

The ribosome attaches to a strand of mRNA at the start codon.

Second step of translation

The tRNA’s 3 base anticodons temporarily bonds with the 3 base codons on the mRNA, bringing the correct amino acid with it to form the proper sequence of the protein.

Third step of translation

Another tRNA moves in and brings in another amino acid. The ribosome makes a bond between the amino acids, beginning the formation of a protein.

Fourth step of translation

The first amino acid is always Methianine, which is coded for by the start codon AUG.

Fifth step of translation

When the ribosome reaches a stop codon, the translation stops. The ribosome detaches from the mRNA. The mRNA may be read by ribosomes over and over until the cell has enough protein.

What is a mutation?

A permanent change in the DNA nucleotide sequence.

What are some types of mutagens?

UV radiation, X-rays, tobacco

If a change in the nucleotide changes the codons, then one or more ______ in the protein chain will be different

Amino acids

These mutations are a change in 1 nucleotide base.

Point

Frameshift mutations are caused by _____ or ______. Causes a shift in which 3 bases are read as a codon.

Insertion, deletion

These mutations are changes in bases that do not alter the amino acid sequence. These occur because amino acids may be coded by several codons.

Silent

DNA structure