DNA What is DNA Contains all genetic information

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DNA

DNA

What is DNA? • Contains all genetic information of the entire organism • Located

What is DNA? • Contains all genetic information of the entire organism • Located in the nucleus of all cells (with a few exceptions!) – mature red blood cells have no nucleus – sex cells have half the amount of genetic information (haploid) • A “full set” in humans is 46 chromosomes – Made up of 23 pairs (diploid)

But not in all animals! Organism # of Chromosome Pairs Human 23 Drosophila (fruit

But not in all animals! Organism # of Chromosome Pairs Human 23 Drosophila (fruit fly) 4 E. coli (bacteria) 4 Mosquito 3 Fly 4 Frog 18 Cat 19 Chimpanzee 24 Horse 32 Dog 39 Onion 8 Peanut 12

 • DNA spends most of its time in a long string called chromatin

• DNA spends most of its time in a long string called chromatin • During cell division, chromatin coils up tightly to form chromosomes

 • the section of DNA that codes for a protein is called a

• the section of DNA that codes for a protein is called a gene

 • DNA -> RNA -> Protein (made of amino acid)

• DNA -> RNA -> Protein (made of amino acid)

DNA Structure • DNA is made of nucleotides composed of 3 parts – 5

DNA Structure • DNA is made of nucleotides composed of 3 parts – 5 carbon sugar: deoxyribose – one nitrogenous base (4 possible options!) – phosphate group • DNA: – Deoxyribo– Nucleic acid

 • There are two types of nitrogenous bases: 1. Purines -Adenine (A) and

• There are two types of nitrogenous bases: 1. Purines -Adenine (A) and Guanine (G) -2 fused rings 2. Pyrimidines -Cytosine (C) and Thymine (T) -only one ring Adenine ALWAYS bonds with thymine Guanine ALWAYS bonds with cytosine -this is called complimentary base pairing

 • When we write information we use 26 letters (plus some extra numbers

• When we write information we use 26 letters (plus some extra numbers and symbols) – Words can be short • Computer information is stored as zeros and ones (binary) – This takes a lot of zeros and ones to give useful information (very long “words”) – E. g. the letter a is 0110001 • How big is the human genome? – Only uses 4 letters (A, C, G, and T)

 • How long do you think the human genome is? (in bases) •

• How long do you think the human genome is? (in bases) • The human genome has approx. 3 billion base pairs – That’s 3, 000, 000 bases! • Printing this out would take roughly 150, 000 telephone book pages

 • DNA looks like a twisted ladder – This arrangement is called a

• DNA looks like a twisted ladder – This arrangement is called a double helix

 • Alternating sugar and phosphates make up the backbone (the “rails” of the

• Alternating sugar and phosphates make up the backbone (the “rails” of the ladder) • Bases make up the “rungs” and are held together by weak hydrogen bonds