Download - DNA
DNA
11
CLIP
DNADNA• locatedlocated in the
nucleus• Function:Function: Carry
genetic material
• Many People contributed to the discovery of DNA.
22
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
People Who Discovered DNA
• 1952 – Rosalind Franklin – DNA = twisted
• 1952 – Edwin Chargraff - #A = #T; #C = #G; Chargraff’s Rule
• 1953 – Watson and Crick – Discovered structure of DNA we know today
4
55
Shape of Shape of DNADNA1.1.Double HelixDouble Helix..
--Twisted ladder or Twisted ladder or spiral staircasespiral staircase
2.2.Two strandedTwo stranded
3.3.Held together by Held together by hydrogen bondshydrogen bonds
4.4.Made of four Made of four NucleotidesNucleotides
66
RememberRemember: :
• DNA is a nucleic acid.
• Nucleic acids are made of nucleotides 77
Structure of Structure of DNADNA
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
88
4 NitrogenousBases
• Adenine• Guanine• Cytosine• Thymine
9
Sides of Sides of the the “Ladder” “Ladder” are made are made up of up of sugar sugar and and phosphatphosphate.e.
1100
AdenineAdenine alwaysalways pairs with pairs with ThymineThymine
CytosineCytosine alwaysalways pairs with pairs with GuanineGuanine
1111
Would Thymine be able to pair up with Guanine?NO!!
1122
1313
22001144
DNA DNA ReplicationReplication
•Before mitosis, the DNA must be replicated (Copied) exactly.
•Each strand can be used to make the other strand.
•Many enzymes are involved.
1515
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.
1616
ChromosomeStructure
• A chromosome has DNA and protein-chromatin.
• Tiny sections of DNA are called genes
1717
Steps:
1. parent/original strands are unwound with the help of DNA helicases (enzymes).
Replication Bubble
1188
Semi-conservative replication
1199
Steps:
2. DNA polymerase attached new nucleotides to the parent strands
2200
How a protein is How a protein is mademade
•TranscriptionTranscription•TranslationTranslation
2222
DNA codes for all of DNA codes for all of the cell proteins.the cell proteins.
2233
24
Overview: • DNA is located in the Nucleus• Proteins are made on the ribosomes.• DNA makes a copy (send a message) called “mRNA”
2255
Two Steps of Protein Synthesis1. Transcription 2. Translation
2266
Transcription• a copy of the DNA is made…the copy
is called messenger RNA or mRNA. • The mRNA takes the code to the
ribosome.
2727
DNA vs. RNA
• Double Stranded
• AGTC
• Deoxyribose
• NEVER!
2288
• Single Stranded
• AGUC
• Ribose
• YES!
DNA Transcription
• During transcription the DNA unzipped and RNA nucleotide are paired up with the DNA bases.
• Website
2299
30
3311
•Once the mRNA copy is made, it can go to the ribosome to be translated.
3322
• Remember….Proteins are made out of amino acids.
• There are 20 different amino acids.
• 3 bases code for each amino acid = codon. 33
33
How you figure out
which codon is coding for
which amino acid…
3344
•Once the mRNA gets to the ribosome, the protein can be assembled.
•Transfer RNA brings the amino acids to the ribosome.
• Website
3355
• 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.
3366
Review Clip
37
Mutations
38
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.
3939
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 mutagens2- Errors that occur when a cell
replicates its DNA in preparation for cell division.
4400
Types of Mutations
41
Point mutation
-a simple change
in a single base of the gene sequence
- 3 Types: 1. Point
2. Insertion3. Deletion
4422
Frame-shift Frame-shift MutationsMutations
In a frame-shift mutation, one or more bases are deleted or inserted, the equivalent of
adding or removing
letters in a sentence.
4343
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
Chromosomal Mutations
• Mutations can occur that involve whole or partial chromosomes– Non-disjunction – homologous chromosomes
don’t separate during meiosis – a gamete ends up with an extra chromosome (ex. Down’s syndrome)
– Crossing Over – parts of homologous chromosomes are swapped during meiosis
43A43A
Results of DNA Mutations
• The results of mutations can be The results of mutations can be • HelpfulHelpful
– They can result in a helpful trait such as They can result in a helpful trait such as better camoflagebetter camoflage
• NeutralNeutral– If the mutation does not cause a change If the mutation does not cause a change
in amino acid sequence, or the replaces in amino acid sequence, or the replaces 1 amino acid with one that is similar, 1 amino acid with one that is similar, the protein will still function the same. the protein will still function the same.
• HarmfulHarmful– A large change in the amino acid A large change in the amino acid
sequence can make a protein that does sequence can make a protein that does not function at all. not function at all.
CLIP
51
44
53
45
Which of the Which of the following is the following is the
correct base-pairing correct base-pairing rule for DNA?rule for DNA?
A A-U; C-GB A-G; T-CC A-T; G-CD A-C; T-G 46
DNA TECHNOLOGY
forensicsforensics
agricultu
re
agricultu
re
DNADNA fingerprintingfingerprinting
medicinemedicine
industryindustry
genetic recombinationgenetic recombination..
4477
4488
DNA FingerprintingDetermining the sequence of bases in DNA for comparisonsHow they identify criminals and do paternity tests (i.e. “Who is my Baby’s Daddy?”)
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.
4499
Who doesn’t belong?
5500
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
5511
•6600
•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
Genetic Engineering
52
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.
•5533
Scientists today have developed Scientists today have developed genetically altered bacteria. genetically altered bacteria. Among them are strains of bacteria Among them are strains of bacteria that that
eat up oil spillseat up oil spillsmanufacture alcohol and other manufacture alcohol and other chemicalschemicalsprocess minerals. process minerals.
There is concern about possible risks There is concern about possible risks to the environment and the general to the environment and the general population as genetically engineered population as genetically engineered bacteria are introduced.bacteria are introduced.
Clip
•5544
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.
•5555
•5555