DNA Structure, Replication, and Mutations: Key Concepts for Biology

Nucleobases

The broken part of the strand

Base Pair

The pair that is stuck together

Sugar phosphate backbone

The alternating chain of sugar and phosphate to which the DNA and RNA nitrogenous bases are attached

Single stranded

RNA, nothing is connected

Double-stranded DNA

the two strands have complementary sequences

What nitrogenous bases are found in RNA?

Adenine, Uracil, Guanine, Cytosine

What nitrogenous bases are found in DNA?

Adenine, Thymine, Guanine, Cytosine

What does the rectangle in a nucleotide represent?

Nitrogenous base

What does the square in a nucleotide represent?

Nitrogenous base

What dies the diamond-square shape in a nucleotide represent?

Sugar

What does the circle in a nucleotide represent?

Phosphate group

What does Chargaff's rule tell us about the bases in a DNA molecule?

It explains how in DNA, Adenine=Thymine and Guanine=Cytosine. A with always equal T, G with always equal C

If a strand of DNA has 32% of Adenine, what is the present of Thymine?

32%

If I have a strand of DNA with the following base pairs, what would be the complementary strand?

A T C C G T T A C G T A G C T

T A G G C A A T G C A T C G A

What is the role of Helicase in DNA replication?

Helicase unwinds or "unzips" the DNA double helix to make it a single strand

What is the role of DNA polymerase in DNA replication?

It helps to build a new DNA strand but also making sure that it is in order.

When DNA is replicated, how much of the original DNA molecule is a part of the new resulting DNA molecule?

50% of the original DNA is in the new DNA

What part of a DNA molecule allows the molecule to "unzip" into two separate strands? (What are we breaking to separate the strands?)

Hydrogen bonds in the DNA molecule let's the molecule unzip.

What are the 3 major kinds of RNA?

mRNA, tRNA, rRNA

What is the function of mRNA?

Messenger RNA carries copies of the genetic instructions from DNA to other parts of the cell.

What is the function of tRNA?

transfers amino acids to ribosomes

What is the function of rRNA?

makes up ribosomes

Transcribe a mRNA molecule from the following DNA strands.

A T T A G G C G G T A G C A T

U A A U C C G G G A U C G U A

Transcribe a mRNA molecule from the following DNA strands.

T G G G C G A A T G C A G T C

A C C C G C U U A C G U C A G

Where in the cell is mRNA translated into a polypeptide chain (protein)?

In the ribosomes

Using the Codon Chart, translate the following strands of DNA in the appropriate amino acid sequences (remember that you need to transcribe the mRNA from the DNA strand first).

TAC TTT ATG CAT TGT ACT

Met (start), Lys, Tyr, Val, Thr, Trp

Using the Codon Chart, translate the following strands of DNA in the appropriate amino acid sequences (remember that you need to transcribe the mRNA from the DNA strand first).

TAG CGC AAT CCT GCA TGA

Lie, Ala, Leu, Gly, Arg, Thr

What is a point mutation?

a mutation affecting only one or very few nucleotides in a gene sequence.

What is a chromosomal mutation?

mutations that produce changes in whole chromosomes

List examples of chromosomal mutation

Deletion, Duplication, Inversion, Translocation

A mutation converts the base cytosine into uracil. If this mutation is not repaired when the DNA replicates, what will most likely happen on the new DNA molecule?

It will be pair differently during DNA replication, causing it to pair with the wrong bond.

What effect does deletion mutation have on a DNA molecule?

It causes a frameshift mutation because it shifts the reading frame of letters which can change every amino acid that comes after the point mutation.

How would a deletion mutation impact the translated protein from this DNA molecule?

It can completely change the protein structure and function