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Ch 12 DNA and RNA. What is DNA?. D NA ( d eoxyribo n ucleic a cid)- a nucleic acid which stores genetic traits in the proteins it codes for. All living things contain DNA. D NA is a n ucleic a cid. Nucleic acids are made of nucleotide subunits hooked together. Nucleotides.

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Ch 12 DNA and RNA

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Ch 12 dna and rna

Ch 12

DNA and RNA


Ch 12 dna and rna

What is DNA?

  • DNA (deoxyribonucleic acid)- a nucleic acid which stores genetic traits in the proteins it codes for.

  • All living things contain DNA.

  • DNA is a nucleic acid.

  • Nucleic acids are made of nucleotide subunits hooked together.


Ch 12 dna and rna

Nucleotides

  • Nucleotides- subunits of DNA made of:

    1. Phosphate (PO4)

    2. Sugar (deoxyribose).

    3. Nitrogen base.


Ch 12 dna and rna

Nitrogen Bases

  • Four different nitrogen bases makes four different nucleotides:

    • Guanine

    • Cytosine

    • Adenine

    • Thymine

  • These four nucleotides make up the DNA of almost every single living thing.


Ch 12 dna and rna

Nucleotides


Chargaff s rule

Chargaff’s Rule

  • He measured amounts of each base in various organisms and found:

  • % of adenine (A) = % thymine (T)

    % of cytosine (C) = % guanine (G)

  • Chargaff’s rule told us that A bonds to T and C bonds to G

  • If 20% of strand is A, what %T? %C?


Structure of dna

Structure of DNA

  • Discovered by Watson and Crick

  • Double helix- 2 spiral strands of nucleotides bonded together


Structure of dna1

Structure of DNA

  • Siderail backbone is the sugar and phosphates of nucleotides

  • Rungs are the nitrogen bases of nucleotides

    • A----T

    • C----G

  • Hydrogen bonds between bases hold two strands together


What is dna replication

What is DNA Replication?

  • Replicate = make “exact” copies.

  • DNA replication- copying of DNA so that a cell made divide

  • All DNA must be replicated before a cell can divide. Why?


Enzymes and replication

Enzymes and Replication

  • Helicase- enzyme that unwinds DNA

  • DNA polymerase-enzyme that moves along each strand and brings in bases for new strand copy


Dna replication

DNA Replication

  • Can be a mistake in replication

  • Mutations-change in DNA

  • Mutagens- substances that cause mutations

    • X-rays

    • Toxins

    • Drugs

    • UV light, etc.


Mutations

Mutations

  • 3 types of mutations that can occur during DNA replication:

    • Insertions -extra nucleotides

    • Deletions –missing nucleotides

    • Substitutions –placement of wrong nucleotides

  • Can be helpful or harmful

    mutations.

Insertion

Deletion

Substitution


Most destructive mutation

Most Destructive Mutation?

  • The bases, A, C, G, and T can be equated to letters of a “DNA sentence”

    THE DOG WAS HOT IN THE SUN

  • Substitution:

    THE DOG WAS NOT IN THE SUN

  • Insertion?

    THE DOG NWA SHO TIN THE SUN

  • Deletion?

    THE DOG ASH OTI NTH ESU N


Ch 12 dna and rna

How Much DNA Is In OUR Cells?

  • Chromosome-strands of DNA coiled tightly

  • Human cell has 46 (23 pairs)

    • 23 from Mom

    • 23 from Dad

  • Other organisms

    have different

    numbers of

    chromosomes


Ch 12 dna and rna

2 Types of Cells

  • Somatic cells –all body cells except sex cells

    • Diploidchromosomes are in pairs

    • 46=23 pairs for humans

    • 1 set (23) from mom, 1 set (23) from dad

  • Gametes - sex cells

    • Egg & sperm

    • Haploid no pairs (only 23 single chromosomes total)

body cells

46 chromosomes

sperm

23 chromosomes

egg

23 chromosomes


Ch 12 dna and rna

Human Chromosomes

  • If all body cells contain the same # of chromosomes, why are all cells so different?

  • Different cells make different proteins due to different “active” segments of DNA.

    • Heart cells make proteins needed for the heart to work properly

    • Brain cells make proteins needed for the brain to work properly


What is the purpose of dna

What is the Purpose of DNA?

  • Gene- a segment of DNA that codes for a protein.

  • DNA has 1000’s of genes to make many different types of proteins.

  • Protein - polymer of amino acids

    aa—aa—aa—aa—aa—aa—aa—aa = protein

  • Why are proteins important?

  • Proteins make up about 15% of the mass of the average person. Muscle, cartilage, ligaments, skin and hair - these are all mainly protein materials.

  • Smaller protein molecules play a vital role in keeping our body working properly. Haemoglobin, hormones (such as insulin), antibodies , and enzymes are all examples of proteins.


What is the purpose of dna1

What is the Purpose of DNA?

  • DNA stores the genetic information that codes for proteins.

  • ALL CELL FACTORIES MAKE PROTEINS!


Rna ribonucleic acid

RNA (Ribonucleic acid)

_____DNA____ vs._____RNA___

Transmits the genetic code

to the rest of the cell.

Single stranded

Sugar of RNA nucleotides is

ribose

A, C, G, U (uracil) NO T!

Different forms: mRNA, rRNA, tRNA

Found all over cell

Stores the genetic code in the nucleus.

Double stranded

Sugar of DNA nucleotides = deoxyribose

A, C, G, T

“DNA is DNA”

Found in nucleus only


Dna vs rna

DNA vs. RNA


Part 1of protein synthesis transcription

Part 1of Protein Synthesis: Transcription

  • Transcription- copying of DNA to mRNA that occurs in the nucleus.

  • DNA complementary to mRNA

  • ATA-CGG-AAT(DNA)

    transcription in nucleus

    UAU-GCC-UUA (RNA)


Part 2 of protein synthesis translation

Part 2 of Protein Synthesis: Translation:

  • Translation- converting mRNA to protein which occurs at ribosomes in the cytoplasm

  • mRNA codons

    translation by ribosomes

    a.a.---a.a---a.a (protein)

cytoplasm


Part 2 of protein synthesis translation1

Part 2 of Protein Synthesis: Translation:

  • Codon-three bases of mRNA that code for an amino acid

  • UAU-GCC-UUA (3 mRNA codons)

    translation by ribosomes

    a.a.---a.a---a.a. (protein)

  • mRNA needs the help of tRNA to bring in the amino acids to be hooked together

cytoplasm


Ch 12 dna and rna

Part #1

Transcription

cytoplasm

Part #2

Translation


Whole process

Whole Process

Part #1

Transcription

ATA-CGG-AAT(DNA)

transcription in nucleus

UAU-GCC-UUA (3 mRNA codons)

translation in cytoplasm at ribosomes

a.a.- a.a - a.a. (protein)

How do we know what amino acid results?

The Codon Wheel!!!

cytoplasm

Part #2

Translation


The codon wheel how do we use the wheel there are 2 clues

The Codon Wheel***How do we use the wheel? There are 2 clues.


The codon wheel

The Codon Wheel


Whole process1

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.

tyrosine-alanine-leucine

Protein Synthesis Animation!

How do we know what amino acid results?

The Codon Wheel!!!


Amino acids

Amino Acids

  • Where do our cells get these amino acids to build the proteins?

  • From FOOD!

  • We eat proteins, then these proteins are broken down (metabolized) into amino acids in our stomach.

  • We reuse these amino acids to build other proteins.


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