DNA Flashcards
What is DNA
Deoxyribonucleic acid is the hereditary material in humans and almost all other organisms.
DNA profile
A bar code pattern from DNA unique to each organism
Hydrogen bond
Weak bond between nitrogenous bases in DNA molecule
Nuclear pores
Openings in nuclear membrane that allow mRNA to leave nucleas.
Peptide bond
Name of bond that forms between amino acids in protein molecule
Replication
Process by which DNA molecule makes identical copies of itself
Ribose
Type of sugar found in an RNA molecule
Transcription
Stage of protein synthesis during which mRNA forms from DNA
Translation
Stage of protein synthesis during which tRNA interprets the message on the mRNA to form a specific protein
tRNA/transfer RNA
Type of nucleic acid that carries a specific amino acid
Uracil
Nitrogenous base found only in RNA molecules
Deoxyribose
A sugar molecule found in a nucleotide of DNA
Function of DNA
Stores an organisms genetic info
Controls the production of proteins.
Where DNA is located
Cell nucleas (nuclear DNA)
Mitochondrion (mitochondrial DNA /mtDNA)
Chloroplast (Chloroplastic DNA)
DNA structure (nucleotide)
Deoxyribose sugar, nitrogenous base, phosphate
Nitrogenous bases & types
Divided into 2 groups which are pyramidines (thymine & cytosine) & purines (adenine & guanine)
Why does a purine not bond with purine & pyramidine not bond with a pyramidine
Only a pyramidine & purine pairing has width consistent with DNA
Purine+purine is too wide
Pyramidine+pyramidine is too narrow
Shape of dna
Double helix
DNA supercoiling
Refers to the over & under winding of strands.
Important for DNA packaging within all cells & reduces the space & allows for much more DNA to be packaged.
Complementary base pairing
When a specific pyramidine base bonds with a specific purine base
Why DNA is called a polymer
It is made up of many nucleotides bonded together
Nucleotide
Building blocks/monomers of nucleic acids
DNA & RNA difference
RNA has : uracil
DNA has: thymine instead
RNA has: ribose sugar
DNA has: deoxyribose
RNA has a single stranded molecule
DNA has a double stranded molecule
Polynucleotide
A very long molecule made up of a string of repeating nucleotides
Rung
Complementary bases joined together in a nucleotide
Non coding DNA
DNA that does not code for the production of proteins (some regions of DNA between genes of chromosome do not code)
Chromosome
A threadlike molecule of DNA made up of many gened
3 DNA Replication purposes
Produce another molecule that is exactly the same
Keep genetic info. constant as it passes down to next generation
Daughter cells to have same no. of chromosomes & genetically identical chromosomes
What happens when cells are genetically different
They don’t work together because they do not recognize each other as being part of same organism
Mutation
When nitrogenous bases are paired incorrectly :
- Enzymes proof read molecule to double check if NB are paired correctly
- Nucleotide is removed & replaced with correct one
DNA replication process
1) An enzyme cause DNA molecule to unwind
2) The enzyme (polymerase) breaks weak complementary hydrogen bonds cause DNA to unzip
3) each original DNA strand acts as a template
4) Free floating nucleotides containing NB attaches itself to template strands (A-T, C-G).
5) Free DNA nucleotides are lined up and join to form a new polynucleotide chain.
6) Results in 2 identical DNA molecules
DNA profile
Procedure used to identify an individuals unique DNA pattern
What can DNA profile be used for
To determine paternity +maternity
Identify dead people
Identify organ donors
Solve crimes
Reliability of DNA profiling
Each individual has unique DNA profile unless they have an identical twin
Which sources can DNA be derived from
Semen
Blood
Hair root
Skin
Saliva
Why DNA profiling evidence may be unreliable
Only small Amt of samples available
Human error: collecting/processing samples
Planting false evidence
Franklin Rosalind role in discovery of dna
Was working on xray diffraction patterns on dna to see what the xray diffraction patterns of DNA would look like
Wilkens role in DNA history
Partner of Franklin who gave her unpublished photographs & measurements to James Watson & Francis crick.
James Watson & Francis crick role in DNA history
Used unpublished photographs & measurements by Franklin to workout correct structure or DNA
They deduced that it was a double helix, the width of DNA, space between NB & discovered bonds between bases. A-T had 2 bonds & C - G had 3 bonds
Who was awarded Nobel prize
Watson, Crick and Wilkens were handed Nobel prize in 1962 but Franklin had already died in 1958
Uses of DNA replication in biotechnology
Cloning cells in tissue culture
DNA profiling
Paternity & maternity testing
Gene splicing
Genetic counseling
Protein Synthesis importance
Building blocks of cells
Control chemical reactions
Form antibodies
Transport material to & from cells
What process attaches amino acids
Dehydration synthesis
(One amino acid is attached to another & some water is released)
Peptide bonds
Types of RNA
Messenger RNA
Ribosomal RNA
Transfer RNA
mRNA
Carries instructions from DNA I’m nucleas to ribosome
rRNA
Combines with proteins to form ribosome (protein made here)
tRNA
Transfers amino acid to ribosome as it is specified by coded messages in the mRNA during construction of protein l
Codon
Set of 3 adjacent nucleotides (in dna/mRNA) that designates a specific amino acid to be included into a polypeptide
Protein Synthesis
Process during which proteins are made beginning in nucleas and ending in ribosome.
Stages of protein synthesis
1) Transcription
2) Translation
Transcription
Process that takes place in nucleas where DNA provides code to make mRNA
Translation
Process in cytoplasm where RNA results in production of protein
Process of Protein Synthesis
1 Enzymes control process
2 Double helix unwinds
3 Weak HB break, strands unzip at required gene (from start to stop codon for gene)
4 One strand acts as template for formation of mRNA
5 Free RNA nucleotides from nucleoplasm attach to complementary bases on dna forming mRNA
6 mRNA moves out of nucleas
tRNA role in translation
Picks up specific free amino acids which aren’t coded for from cytoplasm
Carries the amino acids to ribosome
TRNA attaches itself TO mRNA in complementary manner uses nitrogenous bases an template on ribosome
Amino acid bones together with Peptide bond to form protein molecule
tRNA detaches from mRNA & can be used to bring more amino acids to ribosome
Protein molecule
Amino acids bonded together with Peptide bond producing polypeptide chain until last amino acid is bonded
