Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

DNA Information
 Basic Structure
o Consists of two entwining polynucleotides
...

 The order of nucleobases determines information
...

 Chromosomes
 Composed of two chromatids, held together by a centromere
...

 Chromatin proteins (eg
...

 Humans contain 23 pairs of chromosomes
...

 In females the sex chromosomes are the same (XX)
...

 In males the sex chromosomes are different (XY)
 50% of sperm has X chromosome, 50% of sperm has Y
chromosome
...

 The rest are autosomes
...

 Dark bands are gene rich
...

 When there are two sets of chromosomes in a cell, it is called
diploid, represented by 2n (n being number of chromosomes)
 Sex cells are haploid (represented by n)
 The largest chromosome is Chromosome 1 with more than 4000 genes
...

 Chromosomes can be viewed through light microscopes when cells
divide
...

 Adenine - Uracil in RNA
 Uracil occurs as a breakdown of Cytosine
...

o Cytosine - Guanine (purines) are bonded through 3 hydrogen bonds
...

 Melting temperature (T) is where 50% of ds molecules are converted to ss
molecules
...

Sugar & Phosphate group to nucleobase are bonded covalently
...

o The cell is the basic unit of structure & organization in organisms
...

Genes
o Sections of DNA which code for a characteristic
...

o Each chromosome contains hundreds to thousands of genes at different loci
...
There are 20 000 - 25 000 total genes in a
genome
...

 Sexual reproduction
o Stages
 Interphase
 Chromosomes form, duplicate, and undergo chromosomal crossover
...

Mitosis
o Cells divide to produce daughter cells with the same number of chromosomes as the
parent cells
...

o Stages
 Interphase
 No physical change, but DNA duplicates and so does centromere
...

 Metaphase
 Centrosomes migrate to poles of cell, nuclear membrane breaks down,
microtubules attach to chromosomes and pull them apart
...

 Telophase
 Nuclear membrane reforms around each group and the nucleoli reform
...

People
o Gregor Mendel
 Investigated inheritance in pea plants
...

o











o











Frederick Miescher
 Isolated DNA
o Theodor Boveri & Walter Sutton
 Independently rediscovered Mendel's laws and identified what happens on a
cellular level
...

o Maurice Wilkins & Rosalind Franklin
 Franklin took x-ray diffraction photograph of DNA, and Wilkins passed photo
to Watson & Crick
o James Watson & Francis Crick
 Identified DNA's double helix model in 1953
...

o Helicase unzips the DNA strand
...

o DNA polymerase does the same for the lagging strand in patches
...

Shape
o Double Helix
o Anti-Parallel
Statistics
o Human DNA has over 3 billion bases
...

Transcription
o Purpose - To produce a single strand of messenger RNA (mRNA) whose nucleotide
sequences are complementary to the DNA of source transcription which will act as
an intermediate between the DNA gene and the final protein product
...

 RNA polymerase reads template DNA 3' to 5 and adds complementary RNA
nucleotides from 5' to 3'
...

 Uracil occurs naturally as a breakdown of cytosine
...

 In prokaryotes, this process occurs in the cytoplasm while in eukaryotes it
occurs in the cell nucleus
...

o Process
 Aminoacyl tRNA synthetase attaches amino acids to corresponding tRNA
molecules
...

 Codons are three nucleobases next to each other
...






After all have been dropped when a stop codon (UAG, UAA, UGA) is
encountered, there is a chain of amino acid joining covalently with peptide
bonds making a polypeptide
...




---