DNA and RNA Flashcards
What is DNA ?
DNA is a long double stranded structure
Bases in DNA are adenine, thymine, guanine, cytosine
Genetic code = sequence of 3 DNA bases repeated many times
Each group of 3 bases is the code for an amino acid
Sequence of bases that produce a protein is called a gene
Non coding DNA
Most DNA in a chromosome does not code for any amino acids
Some non coding DNA is found between the genes and some found in the genes
DNA Replication
Double helix unwinds
Enzymes break down hydrogen bonds
Complementary strands move apart
DNA nucleotides move from cytoplasm to into the nucleus and attach to their complementary bases on the exposed strands
The new strands have the same sequence of bases. Each new stretch of DNA ‘re forms into a double helix
EXPERIMENT: To isolate DNA from onion cells
Grind up onion tissue in a salt/detergent (clump DNA/ break down cell membranes)
Filter the mixture (remove cell parts), proteins and DNA form the filtrate
Add protease enzyme to filtrate ( remove protein)
Add ice cold ethanol ( to precipitate the insoluble DNA)
What is a DNA profile
A DNA profile is a unique pattern of DNA from one person that is compared with the DNA profile of another person
How are DNA profiles obtained
Releasing DNA from cells
Cutting the DNA into fragments using restriction enzymes
Separate fragments according to size
Comparing the patterns of the band’s
How are DNA profiles used
Establish weather biological tissue at a crime scene matches or doesn’t match the suspect
Determine whether a person is or is not he parent of a child
What is genetic screening
Means that a person’s DNA can be tested to show the presence of normal or altered genes
What are the differences between DNA and RNA
DNA:
- contains the base thymine
- Double stranded (Double helix)
- Found in th nucleus
RNA:
- Contains the base uracil
- Single stranded
- Found in Nucleus and Cytoplasm
How DNA( or a gene) makes protein
DNA strands separate
The bases on DNA link up with complementary bases to form mRNA (transcribed)
mRNA enters a ribosome
The correct sequence of amino acids is linked together in the ribosome to form a protein ( code is translated)
The protein folds into the correct shape
What is the detailed structure of DNA
DNA consists of….
Nucleotides, which contain phosphate, deoxyribose sugar and a base
The purines—> guanine, adenine
The pyridimines ——> Thymine, cytosine
Bases pairs join together because of hydrogen bonding
A Double helix: Phosphates and sugars form the sides Base pairs are inside the double helix
