DNA: the code of life Flashcards
Full name of DNA
Deoxyribonucleic acid
Organisms with no nucleus
prokaryotes e.g. bacteria
Location of DNA in eukaryotes
Nucleus
Also in:
- Mitochondria in plants and animals
- Chloroplasts in plants
Examples of eukaryotic kingdoms
- plants
- animals
- fungi
- protists
DNA and proteins forming a dense network of fibres in the nucleus
Chromatin
Parts of the nucleus include
- Double nuclear membrane
- Nucleoplasm
- Chromatin/DNA and proteins
- Nucleolus
Phase of a cells cycle when the chromatin condenses into distinct chromasomes
Prophase of Mitosis and Meiosis
How do you make a karyotype & what do we use it for?
- Cut out images of a cells chromosomes
- Arranged in pairs and numbered in order of size
- Shows chromosomal content of cells
- Can be used to diagnose chromosome level genetic disorders
Number of chromosomes in humans
46 chromosomes (23 pairs)
Sex chromosomes for a female and a male
- XX = females
- XY = males
A gene is?
- A specific portion of DNA
- with a specific sequence
- that determines a particular characteristic of an organism.
What exactly do genes code for?
Protein molecules
DNA not containing genes
non-coding DNA
Extra-nuclear DNA often referred to as mtDNA and cpDNA
mitochondrial DNA and chloroplast DNA
Reason for adding salt in a DNA extraction
To condense DNA and proteins after cells have burst
Reason for adding detergent in a DNA extraction
To remove membrane lipids
Reason for adding protease (e.g. meat tenderiser) in a DNA extraction
To remove proteins from membranes and chromatin
Reason for adding ice cold alcohol in a DNA extraction
To purify the DNA as DNA forms a solid precipitate in the alcohol
Initially credited with identifying the double helix structure of DNA
- James Watson
- Francis Crick
- (in 1953)
Performed the X-ray diffraction and photographed it to help discover the structure of DNA
- Rosalind Franklin
- Maurice Wilkins
Repeating units making up DNA are called…
Nucleotides
Composition of one nucleotide
- Phosphate
- Deoxyribose
- Nitrogenous base
The five different nitrogenous bases
- A-Adenine
- T-Thymine
- C-Cytosine
- G-Guanine
- U-Uracil
Purine bases
- Adenine
- Guanine
Pyrimidine bases
- Thymine
- Cytosine
Nitrogenous base pairing (complementary bases)
- A-T (or A-U in RNA)
- C-G
Type of bond between complementary bases
Hydrogen bonds
What are polymers?
Compounds made with repeating units (e.g. DNA)
The method Watson and Crick employed to discover the structure of DNA
Built a model using already known facts about DNA’s composition and structure
The role of DNA
- Carry all the genetic code for an organism
- DNA code is needed for protein synthesis
- Replication provides genetic code for both daughter cells in cell division
- Passing hereditary information from parents to offspring
Phases of the cell cycle
- Interphase, made up of:
- First gap phase (G1) - growth in physical size
- Synthesis phase (S) - DNA replication
- Second gap phase (G2) - checking the cell is ready to divide, and
- Mitosis
Phase of cell cycle when DNA replication takes place
Interphase - Synthesis phase (S)
Errors in DNA code copying during DNA replication that become permanent changes
Mutations
Sequence of steps in DNA replication
- DNA unwinds to form a ladder
- Enzymes unwind and unzip DNA, breaking hydrogen bonds
- Template exposed
- Free floating nucleotides in nucleoplasm
- Enzymes control joining of free nucleotides to existing template
- Forming complimentary strands
- Two DNA strands reform
Identifying someone using their DNA is called
DNA profiling
Main steps in the process of electrophoresis
- DNA loaded into a gel
- Electric current makes DNA migrate towards positive electrode
- Smaller fragments of DNA move faster
- A banding pattern is photographed under ultraviolet light
Process of DNA profiling
- DNA from cells is isolated
- Enzymes cut DNA at very specific sites into different lengths (different for each individual)
- DNA fragments are amplified (copied) by PCR
- Electrophoresis is used to identify the DNA profile
- Banding patterns are compared to known DNA samples
Arguments for use of DNA profiling
- Solve crimes
- Determine paternity
- Find missing persons
- Identify people/ remains
Arguments against use of DNA profiling
- Invasion of privacy for victim and suspect
- Possibility of tampering evidence
- Misuse of technology
Give the complementary DNA sequence for: ACTTCTA
TGAAGAT
