DNA

Question 1

what is DNA?

Answer 1

It is a complex chemical that carries genetic information.

• A molecule made up of repeating units of nucleotides. (this is known as a polymer)

-consists of two antiparallel strands that are held together by hydrogen bonds.

• DNA is located in chromosomes that are found in the nucleus.

Question 2

what are the main 3 components of DNA?

Answer 2

-phosphate ( ⚪ )
- sugar ( ⬠ )
-base ( ▭ )
= one nucleotide

Question 3

what are the 4 different bases?
A T C G

Answer 3

A= Adenine
T= Thymine
C= cytosine
G= guanine

Question 4

what is base pairing?

Answer 4

• A can only link to T (double H bond)
• C can only like to G (triple H bond)

Question 5

What are the differences between DNA and RNA?

Answer 5

DNA:
- Contains deoxyribose sugar
- Has thymine
- Two antiparallel strands

RNA:
- Contains ribose sugar
- Has uracil instead of thymine
- It’s only one single strand.

Question 6

what is a gene?

Answer 6

A gene is defined as a sequence of bases on a DNA molecule that codes for a polypeptide chain.

• A gene occupies a fixed position on a chromosome called a locus.

Question 7

how many chromosomes are there?

Answer 7

Diploid- we have 46 in total
(double)

Haploid- we receive 23 from each parent (half)

Question 8

what is mutation?

Answer 8

Mutation of a gene is the change in the sequence of bases in a strand of DNA.

Question 9

what is Mendel’s second law?

Answer 9

it states that alleles of different genes are inherited independently.

Question 10

what is a genome?

Answer 10

the entire genetic makeup of an individual.

Question 11

what are the three types of RNA?

Answer 11

-mRNA
-rRna
-tRNA

Question 12

what is mRNA?

Answer 12

-formed from DNA in the transcription.

• carries the message that codes for a particular nucleus to the cytoplasm.

-it is single-stranded and contains one gene only.

-short lifespan.

-attached to a ribosome.

Question 13

what is rRNA?

Answer 13

-formed in the nucleus.

-forms half the mass of a ribosome.

Question 14

what is tRNA?

Answer 14

-a single chain that is folded into a clover leaf shape.

-it is found only in the cytoplasm.

-transfers specific amino acids to the surface of the ribosome.

Question 15

what did Erwin Chargaff do in terms of DNA?

Answer 15

WHAT HE DID: arranged nitrogen bases and saw that the DNA varied widely but the number of certain bases always occurred in a 1 to 1 ratio.

WHAT HE FOUND: the ratio of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal.

Question 16

what did Franklin and Wilkins do in turns of DNA?

Answer 16

WHAT THEY DID: used X-ray diffraction meaning they beamed X-ray through DNA molecule yielded in a shadow picture.

WHAT THEY FOUND: double helix structure.

Question 17

what did Watson and Crick do in terms of DNA?

Answer 17

WHAT THEY DID: they did X-ray crystallography revealing the helical shape of the DNA molecule.

WHAT THEY FOUND: DNA is made up of two chains of nucleotide pairs that encode the genetic information for all living things.

Question 18

what does a sequence of three bases called the triplets/codon code for?

Answer 18

amino acids.

Question 19

how to calculate the number of amino acids from bases:

Answer 19

there are 180 bases in the length of DNA, how many amino acids does it have?

• 180 / 3 = 60
  (in 1 amino acid there are 3 bases made)

this means there are 60 amino acids present.

Question 20

what is a phenotype?