Upload
uriel
View
29
Download
0
Tags:
Embed Size (px)
DESCRIPTION
DNA, Genes and Genetics. What is DNA?. - DNA Stands for D eoxyribo N ucleic A cid -DNA is the hereditary material inherited from past generations -The vast majority ( >99%) of your DNA is in the nucleus of your cells. DNA Structure. - PowerPoint PPT Presentation
Citation preview
DNA, Genes and Genetics
What is DNA?
-DNA Stands for DeoxyriboNucleic Acid
-DNA is the hereditary material inherited from past generations
-The vast majority ( >99%) of your DNA is in the nucleus of your cells
DNA Structure-DNA’s structure is known as
a double helix. (Think of a twisted ladder)
-The helix is composed of two strands
-The sides of the ladder (red in the picture) are composed of alternating deoxyribose sugar and phosphate molecules
-The rungs of the ladder are composed of nucleotides held together by hydrogen bonds
NucleotidesAdenine and guanine are known as purines
Cytosine and thymine are known as pyrimidines
A always binds to TC always binds to G
Watson and Crick
James Watson Francis Crick-“Discovered” the structure of DNA in 1953
-Used the knowledge of many other scientists to determine the structure
-Awarded the Nobel prize in 1962 for DNA’s structure*
What are Genes?Genes are segments of DNA responsible for the production of a functional protein.
Every person has two copies of each gene,one inherited from each parent.
Genes are responsible for your traits! Ex. widow’s peak, skin tone, etc
Environment can be a factor in traits as well*
ChromosomesChromosomes are compact molecules of
DNA
A human set of chromosomes contains 23 pairs
23rd pair are your sex chromosomes
Karyotype
Sex chromosome abnormalitiesXXX – Triple X syndrome (1 in 1000)
-little to no effectXXY – Klinefelters syndrome (1 in 1000)
-often infertile, taller, slight reading/ learning impairment, increased breast tissueXYY – XYY syndrome (1 in 1000)
-increased growth velocity-severe acne? -slight developmental delays
(reading and writing)
So how we get from DNA to Protein?
TranscriptionDNA is copied into messenger
RNA (mRNA) by an enzyme called RNA polymerase in the nucleus
RNA is identical to DNA except Thymine (nucleotide) is replaced by Uracil
RNA is single stranded
Transcription
TranslationmRNA is then exported to the
cytoplasm and processed further by other enzymes to remove the “junk” DNA called introns
The final mRNA is transported to ribosomes where translation occurs.
Ribosomes read the mRNA in multiples of 3 nucleotides called codons
For example:5’ AUGCCCUCAGAG 3’
Codon Table
AUG, AUA, and GUA -causes the protein to STOP being translated
AUG (Methionine)-required to START translation
TranslationEach codon signals the cell to
retrieve and add an amino acid to a growing chain of amino acids using transfer RNA (tRNA).
AA sequence = Protein!Once the entire mRNA
sequence is read and translated into amino acids the chain of AA’s is released
This chain of AA’s folds and contorts into a structure called its tertiary structure*
Finally a functional protein!