Tuesday January 29 th 2013 QU: What holds all of your genetic information? Where is it located? OBJ: New Seats, Introduction to DNA

INTRO TO DNA

DNA Structure DNA is located in the nucleus – DNA stands for DEOXYRIBOSE NUCLEIC ACID DNA is a type of nucleic acid – Like starch is a type of carbohydrate DNA is made of repeating subunits called NUCLEOTIDES

Chromatin In the nucleus, DNA is found on long, thin fibers called Chromatin – Chromatin consists of DNA wound around proteins called histones – Next the DNA is wrapped into a tight helical formation

Chromosomes When a cell is preparing to divide, chromatin condense into chromosomes The human somatic cell (body cell) has 46 chromosomes = diploid – 23 from mom + 23 from dad = 46 total – An egg and sperm cell only has 23 = haploid

Chromosomes Before a cell divides, it replicates all of its chromosomes Each chromosome now consists of 2 identical joined copies called sister chromatids Each sister chromatid is joined by a centromere

Chromosome Sister Chromatids

Genes A section of DNA that codes for a specific trait You have thousands and thousands of genes

QU: When DNA is coiled up what is it called? OBJ: Discovering DNA Structure WedNesday January 30 th 2013

Nucleotide

There are 4 different types of nucleotides that can be used to build DNA – This is because there are 4 different nitrogen bases that can be used Adenine (abbreviated A) Guanine (G) Thymine (T) Cytosine (C) DNA

PURINE: Have two rings – To be PURE is Always Good. Adenine and Guanine PYRIMIDINE: Have only one ring – The other two Cytosine and Thymine DNA: Purine versus Pyrimidine

DNA overall structure is called a DOUBLE HELIX DNA *Strands are connected by hydrogen bonds* (between bases)

2 strands of DNA are Complementary

QU: Write the complement to the following strand. A T G C C G T A OBJ: DNA Replication “The most poisonous snake in the world is Belcher's Sea Snake or the Faint- banded Sea Snake (Hydrophis belcheri).” Thursday January 31 st 2013

DNA Replication If I said a painting was a replica (or replicated) what does that mean? Why do you think it is important that we can replicate DNA?

New nucleotides come in and base pair with the “open” original strand. Results in two strands of DNA The DNA has been copied Each DNA molecule has one original strand and one new strand DNA Replication… Process of copying the DNA molecule Original DNA strand Nitrogen bases paired up according to base pairing rules DNA Polymerase separates the bases by breaking the hydrogen bonds holding them together

This type of replication is known as semi- conservative replication – Start with one helix split into two separate strands but never “throw away any strands” Replication

Friday FebRuary 1 st 2013 QU: Replication is __________ because the strands are split and each strand is used in a new DNA molecule. OBJ: Quiz, Replication, Replication Review