DNA

1
DNA
DNA
CLIP
1
2
DNA

• located in the nucleus
• Function Carry genetic material
• Many People contributed to the discovery of DNA.

2
3
People Who Discovered DNA

• 1928 Frederick Griffith - DNA carrier of
  genetic info
• 1944 Avery Genes composed of DNA
• 1952 Hershey and Chase genetic material
  DNA, not protein

3
4
People Who Discovered DNA

• 1952 Rosalind Franklin DNA twisted
• 1952 Edwin Chargraff - A T C G
  Chargraffs Rule
• 1953 Watson and Crick Discovered structure of
  DNA we know today

4
5
What we Know Now........
5
6
Shape of DNA

• Double Helix.
• -Twisted ladder or spiral staircase
• Two stranded
• Held together by hydrogen bonds
• Made of four Nucleotides

6
7
Structure of DNA

• Remember
• DNA is a nucleic acid.
• Nucleic acids are made of nucleotides

7
8
Nucleotides

• DNA long chain of nucleotides
• 4 that make up DNA
• Have 3 parts a sugar molecule (deoxyribose), a
  phosphate group, and a nitrogenous base

8
9
4 NitrogenousBases

• Adenine
• Guanine
• Cytosine
• Thymine

9
10
Sides of the Ladder are made up of sugar and
phosphate.
10
11
Adenine always pairs with ThymineCytosine always
pairs with Guanine
11
12
Would Thymine be able to pair up with Guanine?
NO!!
12
13
13
14
DNA REPLICATION
DNA Replication
20
14
15
DNA Replication

• Before mitosis, the DNA must be replicated
  (Copied) exactly.
• Each strand can be used to make the other strand.
• Many enzymes are involved.

15
16
Chromosome Structure

• DNA is packed very tightly as chromosomes in the
  nucleus.
• Human nucleus has 1 meter of DNA!
• Smallest human chromosome has 30 million base
  pairs.

16
17

• Chromosome
• Structure
• A chromosome has DNA and protein-chromatin.
• Tiny sections of DNA are called genes

17
18

• Steps
• parent/original strands are unwound with the help
  of DNA helicases (enzymes).
• Replication Bubble

Semi-conservative replication
18
19
Replpication Bubbles
19
20

• Steps
• 2. DNA polymerase attached new nucleotides to the
  parent strands

20
21
DNA replication website
21
22

• How a protein is made
• Transcription
• Translation

22
23

• DNA codes for all of the cell proteins.

23
24
DNA Transcription
24
25

• Overview
• DNA is located in the Nucleus
• Proteins are made on the ribosomes.
• DNA makes a copy (send a message) called mRNA

25
26
Two Steps of Protein Synthesis

• 2. Translation

• 1. Transcription

26
27

• Transcription
• a copy of the DNA is madethe copy is called
  messenger RNA or mRNA.
• The mRNA takes the code to the ribosome.

27
28
DNA vs. RNA

• Single Stranded
• AGUC
• Ribose
• YES!

• Double Stranded
• AGTC
• Deoxyribose
• NEVER!

28
29
DNA Transcription

• During transcription the DNA unzipped and RNA
  nucleotide are paired up with the DNA bases.
• Website

29
30
DNA Translation
30
31
31
32

• Once the mRNA copy is made, it can go to the
  ribosome to be translated.

32
33

• Remember.Proteins are made out of amino acids.
• There are 20 different amino acids.
• 3 bases code for each amino acid codon.

33
34
How you figure out which codon is coding for
which amino acid
34
35

• Once the mRNA gets to the ribosome, the protein
  can be assembled.
• Transfer RNA brings the amino acids to the
  ribosome.
• Website

35
36

• The three letter code on the mRNA is called a
  codon.
• The three letter code on the tRNA that is matched
  up with the mRNA is called an anticodon.

36
37
Review Clip
37
38
Mutations
38
39
Mutations

• A sudden change in the genetic code is called a
  mutation.
• Most mutations have little or no effect on the
  organism.
• Mutations can be spontaneous or may be caused by
  environmental factors called mutagens.

39
40
Mutations in DNA usually occur through one of
three processes

• 1- DNA damage from environmental agents such as
  ultraviolet light (sunshine) or nuclear radiation
• Certain chemicals called mutagens
• 2- Errors that occur when a cell replicates its
  DNA in preparation for cell division.

40
41

• Types of Mutations

41
42

• Point mutation
• -a simple change in a single base of the gene
  sequence
• 3 Types
• Point
• Insertion
• Deletion

42
43

• Frame-shift Mutations
• In a frame-shift mutation, one or more bases are
  deleted or inserted, the equivalent of adding or
  removing letters in a sentence.

Original THE CAT ATE THE RAT Deletion THE CAT
ATE THE RAT THE CTA TET HER AT Insertion THE CAT
ATE THE RAT THE CAT ATT ETH ERA T
43
44
Chromosomal Mutations

• Mutations can occur that involve whole or partial
  chromosomes
• Non-disjunction homologous chromosomes dont
  separate during meiosis a gamete ends up with
  an extra chromosome (ex. Downs syndrome)
• Crossing Over parts of homologous chromosomes
  are swapped during meiosis

43A
45
Results of DNA Mutations

• The results of mutations can be
• Helpful
• They can result in a helpful trait such as better
  camoflage
• Neutral
• If the mutation does not cause a change in amino
  acid sequence, or the replaces 1 amino acid with
  one that is similar, the protein will still
  function the same.
• Harmful
• A large change in the amino acid sequence can
  make a protein that does not function at all.

CLIP
51
44
46
53
45
47
Which of the following is the correct
base-pairing rule for DNA? A A-U C-G B A-G
T-C C A-T G-C D A-C T-G
46
48

• DNA TECHNOLOGY

industry
DNA fingerprinting
agriculture
medicine
genetic recombination.
forensics
47
49
DNA Fingerprinting Determining the sequence of
bases in DNA for comparisons How they identify
criminals and do paternity tests (i.e. Who is my
Babys Daddy?)
48
50

• How DNA Fingerprinting works
• Scientist cut up DNA into pieces using enzymes
• Then load the pieces into a gel.
• Electricity is run through the gel.
• The pieces of DNA move to the other end of the
  gel.
• Smaller pieces move farther.

49
51
Who doesnt belong?
50
52

• Recombinant DNA
• is a form of artificial DNA where DNA combined
  that would not normally be combined.
• They cut, splice together, and insert the
  modified DNA molecules from different species
  into bacteria or another type of cell that
  rapidly replicates and divides.
• The cells copy the foreign DNA right along with
  their own DNA.
• Example goldfish have genes for fluorescent
  proteins that have been inserted

51
53
Genetic Engineering

• the manipulation of an organisms genes
• applications in medicine and the environment,
  industry, and agriculture.
• Sheep are used in the production of alpha-1
  antitrypsin, which is used in the treatment of
  emphysema.
• Goats are also producing the CFTR protein used in
  the treatment of cystic fibrosis.
• Crops are being devised that have natural insect
  repellants

• 60

52
54
Genetic Engineering Example In the plant world,
the buds of cotton plants are vulnerable to worm
attacks. The buds of a modified cotton plant
resist these worms, resulting in increased cotton
production. These gene insertions are
ecologically safer than pesticides. They affect
only the targeted pest.

• 53

55
Clip

• Scientists today have developed genetically
  altered bacteria.
• Among them are strains of bacteria that
• eat up oil spills
• manufacture alcohol and other chemicals
• process minerals.
• There is concern about possible risks to the
  environment and the general population as
  genetically engineered bacteria are introduced.

• 54

56
Cloning

• Occurs when the DNA from an adult is inserted
  into the fertilized egg of the organism.
• Results in an offspring that is genetically
  identical to the parent.
• The DNA in the egg must be removed before the new
  DNA is inserted.
• Has been used in animals and plants, hopes for
  the future to allow for the cloning of organs.

• 55

57

• 55