Genetics Unit Genetic Materials • Terms to know: - DNA - genome - RNA - double helix - Chromosome - karyotype - Chromatin - Sister chromatid - Gene - Bases - Nucleotide - Proteins
Dec 24, 2015
Genetics UnitGenetic Materials
• Terms to know:- DNA - genome- RNA - double helix- Chromosome - karyotype- Chromatin- Sister chromatid- Gene- Bases- Nucleotide- Proteins
Rosalind Franklin (1920 - 1958)
X-ray diffraction patterns of DNA
Her essential work was not recognized by the Nobel Committee in 1962
DNA structure
- DNA is made up of two strands arranged in a double helix structure
- The 2 strands of DNA run anti-parallel to one another
DNA = deoxyribosenucleic acid
DNA structure (cont.)The building block of
DNA is called a nucleotide which is made of 3 parts:
- A phosphate group
- A 5-carbon deoxyribose sugar
- A nitrogen- containing base (A,T,G,and C)
http://www.dnalc.org/resources/3d/
Nitrogen-containing bases of DNA- All organisms have the same 4 bases: Adenine Guanine Thymine Cytosine - A connects with T via 2 hydrogen bonds (A=T)- G connects with C via 3 hydrogen bonds
(G≡C)- Only 4 bases but unlimited ways to code for
proteins (proteins are products of genes)
http://www.dnalc.org/resources/3d/25-basepairing.html
Where is DNA? In the nucleus
Human cell: 23 pairs of chromosomes in every non-sex cell
http://www.dnalc.org/resources/3d/07-how-dna-is-packaged-basic.html
Chromosomes= super-coiled DNA
- Male 46 chromosomes = 23 pairs- Karyotype = a picture of chromosomes arranged in pairs
DNA vs. RNA (ribose nucleic acid)
RNA: single strandedThe nitrogenous bases in DNA are: A, T, C, GThe nitrogenous bases in RNA are: A, U, C, G
Molecular Visualizations of DNA
• http://www.youtube.com/watch?v=-1ZvsYDTxc8&feature=related (Part 1)
• http://www.youtube.com/watch?v=S8DMoDJ8FWA&feature=related (Part 2)
Gene- Genes are small segments on DNA that code for proteins
-Proteins are the products of genes
- A gene can range from 1,000 bases to 1 million bases in humans.
- DNA can have thousands of genes.
- Genes can overlap each other
Examples of Proteins
Proteins Functions
Insulin Enzyme for sugar metabolism
Hemoglobin Oxygen transport in blood
Keratin Forms hair, nails and skin
Actin, myosin Movement
Antibodies Body immune system
Genome = is an organism’s complete set of DNA, including all of its genes
Numbers of Pairs of Chromosomes in Different Species of Plants and Animals
Common name Species Number of chromosome pairs
Mosquito Culex pipiens 3
Housefly Musca domestica 6
Garden onion Allium cepa 8
Rice Oryza sativa 12
Frog Rana pipiens 13
Alligator Alligator mississipiensis 16
Cat Felis domesticus 19
House mouse Mus musculus 20
Human Homo sapiens 23
Potato Solanum tuberosum 24
Donkey Equus asinus 31
Horse Equus caballus 32
Dog Canis familiaris 39
Chicken Gallus domesticus 39
Carp Cyprinus carpio 52
Before a cell can divide • It must duplicate its chromosome number (i.e. making 2
copies of each)e.g. if the cell has 2 chromosomes, after DNA duplication it
should have 4 chromosomes Diploid cells: have 2 sets of
chromosomes; often are non-sex or somatic cells; represented as 2n
e.g. Human skin cells contain 2n=46 chromosomes --> they are diploid cells
Haploid cells: have 1 set of chromosomes; are sperm & egg cells; represented as n
e.g. Human sperm and egg cells contain n= 23 chromosomes --> they are haploid cells