2. DNA (deoxyribonucleic acid).
All living things contain DNA.
Source of genetic traits.
DNA is a nucleic acid.
Nucleic acids are made of
nucleotides.
3. Nucleotides
Made of three
things:
1. Phosphate
(PO4)
2. Sugar
(deoxyribose).
3. Nitrogen base.
5. Chargaff’s Rule
He measured amounts of each
base in various organisms and
found:
amt of adenine (A) = thymine (T)
amt of cytosine (C) = guanine (G)
This meant that A bonds to T
and C bonds to G
If 20% of strand is A, what %T?
%C?
6. Structure of DNA
Discovered by Watson and Crick
Double helix- “spiral staircase”, 2
strands of nucleotides
Siderails-sugar and phosphate
Rungs-nitrogen bases
– A----T
– C----G
Hydrogen bonds (glue)
7. What is DNA Replication?
Replicate = make “exact” copies.
All DNA must be replicated before a cell can
divide. Why?
Why do cells need to divide?
1.Growth.
2.Repair or replace
damaged cells.
3.Regenerate body parts
(not all things can do this).
8. Enzymes and Replication
Helicase- unwinds DNA
DNA polymerase-moves along each strand
and brings in bases for new strand copy
9. DNA Replication
Can be a mistake in replication
Mutations-change in DNA
Caused by mutagens, such as X-rays,
toxins, drugs, UV light, etc.
Can cause disease, such as cancer,
cystic fibrosis, etc.
Can be:
– insertions of extra bases
– deletions of bases
– substitutions of the wrong bases.
11. How Much DNA Is In Our Cells?
Chromosome-strands of DNA coiled tightly
Human cell has 46 (23 pair 2 sets of 23)
23 from Mom
23 from Dad
12.
13. If all body cells contain the same # of
chromosomes, why are all cells so
different?
Different cells make different proteins.
Different “active” segments of DNA.
During early stages of development, cells
become “specialized.”
14. The first few cells that develop from
the zygote are called stem cells.
Stem cells differentiate into other
cells.
15. 2 Types of Cells
Body cells somatic
diploidchromosomes are in pairs (23 pairs)
Reproductive cellsgametes
egg & sperm
haploid no pairs (23)
16. What is the Purpose of DNA?
The cell “factory” makes proteins.
Gene- a segment of DNA that codes for a
protein.
DNA has 1000’s of genes to make many
different types of proteins.
– Fingernails, hair, enzymes, hemoglobin, etc.
Protein - polymer of amino acids
18. RNA (Ribonucleic acid)
_____RNA____vs._____DNA___
single strand double strand
sugar= ribose sugar= deoxyribose
A, C, G, U (uracil) A, C, G, T
mRNA, rRNA, tRNA “DNA is DNA”
all over nucleus only
20. Part 1of Protein Synthesis:
Transcription
Transcription: DNA RNA (messenger)
Occurs in nucleus
DNA complementary to mRNA
DNA: ATA-CGG-AAT
transcription in nucleus
mRNA: UAU-GCC-UUA
21.
22. Part 2 of Protein Synthesis:
Translation:
Translation: mRNA protein
Occurs at ribosomes in cytoplasm
Codon-Three bases on mRNA that code for
an amino acid
mRNA: UAU-GCC-UUA (3 codons)
translation in cytoplasm
protein: a.a.---a.a---a.a.
mRNA needs the help of tRNA to bring in
the amino acids
23. Whole Process
DNA: ATA-CGG-AAT
transcription in nucleus
mRNA: UAU-GCC-UUA(3 codons)
translation in cytoplasm
protein: a.a.-a.a-a.a.
How do we know what amino acid results?
The Codon chart or wheel!!!