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Deoxyribonucleic Acid

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Title: Deoxyribonucleic Acid


1
Deoxyribonucleic Acid
The Structure of DNA
2
DNA is
  1. Blueprint of life
  2. Instructions for making proteins
  3. Found in our chromosomes
  4. All of these

3
Why do we study DNA?
  1. Very important to life
  2. For the medical benefits
  3. Better food crops
  4. All of these

4
DNA
  • Called the blueprint of life
  • Contains the instructions for making proteins
  • Discovered by Watson and Crick in 1953
  • NoteRosalind Franklin
  • Made the discovery, she died.

5
Why do we study DNA?
  • Central importance to all life on Earth
  • Medical benefits such as cures for diseases
  • Better food crops.

6
Chromosomes and DNA
  • Genes are on our chromosomes
  • Chromosomes are DNA

7
The Shape of the Molecule
  • DNA is a very long polymer.
  • Shaped like a twisted ladder or zipper.
  • Called a double helix

8
One Strand of DNA
phosphate
  • Backbone is alternating phosphates and
    deoxyriboses
  • Rungs are nitrogenous bases

deoxyribose
bases
9
One Strand of DNA
nucleotide
  • Polymer of nucleotides.
  • Sequence of nucleotide bases determines type of
    protein
  • Many millions of nucleotides.

10
Nucleotides
  • One deoxyribose together with its phosphate and
    base make a nucleotide

Nitrogenous base
O
Phosphate
C
C
C
Deoxyribose
O
11
What is located on our chromosomes?
  • Jeans
  • Ribosomes
  • Genes
  • Proteins

12
Who discovered DNA?
  1. Robert Hooke
  2. Watson and Crick
  3. Crick and Hooke
  4. Watson and Hooke

13
The shape of the DNA molecule is called
  1. Double ladder
  2. Double helix
  3. Double string
  4. None of these

14
The backbone of the DNA is alternating
  1. Phosphate and base
  2. Phosphate and ATP
  3. Phosphate and deoxyribose
  4. Deoxyribose and base

15
What is the subunit of DNA?
  1. Nucleus
  2. Nucleolus
  3. Nucleoplasm
  4. Nucleotide

16
The protein made is determined by
  1. Number of nucleotides
  2. Sequence of nucleotides
  3. Type of nucleotide
  4. None of these

17
Four nitrogenous bases
DNA has four different bases
  • Cytosine C
  • Thymine T
  • Adenine A
  • Guanine G

18
Two Kinds of Bases in DNA
N
  • Pyrimidines are single ring bases
  • Cytosine/thymine
  • Purines are double ring bases
  • Adenine/guanine

C
N
C
C
O
C
N
19
Hydrogen Bonds
  • Bases held together by hydrogen bonds
  • Cytosine always pairs up with guanine
  • CG
  • Adenine always pairs up with thymine
  • AT

Hydrogen bond
20
DNA by the numbers
  • Cell has about 2 m of DNA
  • Average human has 75 trillion cells
  • Average human has enough DNA to go from the earth
    to the sun more than 400 times
  • DNA has a diameter of only 0.000000002 m

21
Show Video
  • http//sciencenetlinks.com/interactives/dna.swf

22
What is the correct base pairing?
  1. C-T and G-A
  2. G-T and C-A
  3. A-T and G-C
  4. A-C and T-A

23
Pyrimidines have.
  1. Single ring
  2. Double ring
  3. Triple ring
  4. All of these

24
Bases are held together by
  1. Peptide bonds
  2. Covalent bonds
  3. Ionic bonds
  4. Hydrogen bonds

25
Replication
  • Before a cell divides
  • Makes two exact copies

26
Process
  • DNA unwinds
  • Enzyme DNA Helicase unzips the DNA molecule
  • Unpaired nucleotides bond with free floating
    nucleotides with the aid of DNA polymerase
  • Process goes in both directions
  • One old original strand and one new strand

27
Process of making an exact copy of DNA is
  • Transcription
  • Translation
  • Replication

28
What is the name of the enzyme that unzips DNA?
  1. RNA polymerase
  2. RNA Helicase
  3. DNA Helicase
  4. DNA polymerase
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