Molecular Genetics & Genetics Flashcards
Molecular Genetics
The branch of genetics concerned with the structure and activity of genetic material at the molecular level
Genetic Material
- Chromatin (chromosomes) within the nucleus of the cell
- contains the entirety of an organisms hereditary information = its genome
- the info is encoded in DNA
DNA structure
- discovery credited to Watson and Crick based off the work of Rosalind Franklin
- Long, double stranded, twisted structure (double helix) composed of nucleotides
Nucleotides
1 nucleotide = phosphate + deoxyribose sugar + nitrogen base
Nitrogen Bases
Found in DNA and RNA nucleotides
DNA : Adenine, Thymine, Cytosine, Guanine
C&T = pyrimidines = single ring
A&G = purines = double ring
RNA : Adenine. URACIL, Cytosine, Guanine
Genes
- Sections of chromosomes associated with specific traits
- Provide the instructions for the manufacture of all the traits within an organism
= proteins
What provides the genetic code for a trait?
Since chromosomes are composed of DNA, its the sequence (order) of the base pairs of the nucleotides that provides the genetic code or instructions for a trait.
DNA replication (what is it)
- Is the doubling of chromosomes during interphase of the cell cycle
- assures that every cell has identical genetic information after cell division takes place
= mitosis and meiosis
Steps of DNA Replication
- UNCOIL: DNA molecule uncoils (gets all long)
- UNZIP: DNA molecule unzips creating 2 parent strands = helicase enzyme breaks hydrogen bonds between base pairs
- REBUILD: DNA molecule rebuilds = DNA polymerase enzyme attaches free nucleotide to corresponding bases of each parent
- RECOIL: Both molecules recoil allowing for mitosis or meiosis to begin again
Why is DNA replication known as semi-conservative?
Because the parent strand is used as a template during the rebuilding of the DNA strands. This means that each new copy contains one original strand and one newly synthesized strand.
= lessens the chance of errors
Proteins
- Large complex molecules made up of amino acids that make up the traits of an organism
= make up all traits in the body (blonde hair, tongue rolling) - It is the number and order of amino acids within a protein that determines the type of protein present.
Protein Synthesis
- the process through which cells make proteins (= making of traits on a molecular level) by using instructions on the DNA
= the sequence of the nitrogenous bases in a DNA molecule provide the chemical code (instructions) for protein
Which acid helps DNA synthesize proteins?
Ribonucleic Acid
RNA Structure
- Single stranded molecule (1 side of ladder)
- made of nucleotides containing ribose sugar instead of deoxyribose sugar
- Uracil instead of thymine
mRNA (messanger)
= the BLUEPRINT for protein construction
- carries building instructions from nucleus to the ribosomes
- on a mRNA strand three adjacent nitrogen bases are called a codon and correspond to an amino acid
Codon
Three adjacent nitrogenous bases which correspond to an amino acid
rRNA (ribosomal)
- CONSTRUCTION site where protein is made
- is the part of the ribosome mRNA attaches to
tRNA (transfer)
- DELIVERS proper amino acids to the right site at the right time
- one end of molecule has an attachment site for amino acids , other side has anti-codon (three bases which match the complementary codon on mRNA)
Transcription : Protein synthesis
- occurs in nucleus = uses DNA to make RNA
- UNCOIL : DNA uncoils (enzyme breaks H bonds)
- UNZIPS : DNA unzips (only one side of DNA will be transcribed)
- CONSTRUCTION : mRNA is constructed out of free nucleotides
- RECOIL : after mRNA is made, H bonds reform and DNA recoils
- TRAVEL : mRNA leaves the nucleus and carries the code to the ribosomes in the cytoplasm
Translation : protein synthesis
- on ribosomes = construction site of the amino acid sequence (protein)
1. ATTACH : mRNA attaches onto ribosome and is “read” by helper enzymes
2. CARRY : tRNA picks up free nucleotides in cytoplasm and carries them to the mRNA
3. Codons on mRNA determine the order amino acids are delivered by tRNA
4. as the process goes on, amino acids are fused into a chain = protein
Mutations
= a change in the genetic makeup of a chromosome which can be passed on
- generally recessive and passed down onto future generations of offsprings
- can be beneficial, harmful or no effect
- induced mutations caused by mutagenic agents like temp, chemicals, radiation
Gene mutations
- Caused by portions of DNA which make up chromosomes being deleted, duplicated, inverted or translocated
- it only affects small part of a chromosome meaning,
= change is no phenotypical (not visable)
= usually results in enzyme deficiency ex) lactose intolerant
Chromosomal mutation
caused by
1. nondisjunction : failure of a chromosome to split during meiosis resulting in gametes having an extra or too few chromosomes
2. translocated or deletion of an arm of a chromosome
- because change affects large portion of or whole chromosome
= change is phonotypical (looks dif than rest of species)
= results in genetic syndromes
Karyotype
- Diagnostic tool used to identify chromosomal mutations
- micrograph picture taken during prophase 1 of meiosis
- Chromosomes are arranged by size and identified by number
- used to diagnose syndromes & disorders
