DNA PROCESSES Flashcards
What is the organization in DNA?
Within the nucleus, there are chromosomes that are coiled up DNA
A gene is a short section of DNA
All the DNA in the body make up a genome
What is DNA used for?
Deoxyribonucleic acid - chemical instructions
Each gene in DNA codes for a specific protein
These proteins control processes in the body, determine and control our inherited characteristics
What is an allele?
Multiple versions of the same gene, that express different types of characteristics
What are the components in DNA?
DNA is in the shape of a double helix, 2 strands coiled around each other
These strands are a sugar phosphate backbone
The strands are held together by 4 bases that pair with each other:
Adenine-Thymine
Cytosine-Guanine
What is RNA?
Ribonucleic acid -
There is only 1 strand, and instead of Thymine, there is Uracil
What is protein synthesis?
The process by which proteins are created by DNA
There are 2 main phases:
Transcription and Translation
What is the process of transcription?
This occurs in the nucleus
Within the chromosome, a DNA unzips, separating the 2 strands
A complementary RNA strand joins to the template strand of the DNA, with the base pairings matching up
Messenger RNA (mRNA) forms, and passes out of the nucleus joining to a ribosome in the cytoplasm
What is the process of translation?
The mRNA binds to a ribosome and the protein begins to be formed
Transfer RNA (tRNA) carries amino acids to the ribosome
There are sets of 3 bases on the mRNA called codons,
and a complementary anticodon on the tRNA
The ribosome joins together the codon/anticodon and creates a amino acid, and multiple amino acids join to form a protein
After an amino acid is created, an empty tRNA moves away, to be used in future for another amino acid
The first tRNA binds to the mRNA’s start codon - always AUG, that codes for methionine and signifies the start of the protein
The last tRNA binds to the mRNA’s end codon, that signifies the end of the chain and the complete protein
What is mitosis?
A type of cell division, where the 2 cells produced are genetically identical to the original cell
It is used for asexual reproduction and for growth and repair of an organism
What is the process of mitosis?
There are 4 phases with mitosis, starting from an undivided cell:
Prophase - the chromosomes begin clumped up, and prophase is where the chromosomes spread out and are visible by a microscope
Metaphase - the chromosomes are aligned down the middle of the cell, held by spindle fibres
Anaphase - the spindle fibres pull apart the chromatids to the poles of the cell
Telophase - 2 new nuclei form at the poles of the cell, and the cytoplasm divides by cytokinesis producing 2 daughter cells
What is meiosis?
Another type of cell division, where the 4 cells produced are unique compared to the parent cell
In humans, occurs in the reproductive system
What is the process of meiosis?
The process is split up into 2 phases:
Meiosis 1 - the chromosomes in the cell form homologous pairs, lining up along the middle
Those pairs are pulled apart, so the new cells have a copy of the father’s and mother’s chromosomes
The cell splits and 2 cells form
Meiosis 2 - the chromosomes align along the centre, and the chromatids are pulled apart by spindle fibres
The cells split again forming 4 gametes that have a single set of chromosomes, and are unique from the parent cells, with genetic variation between the gametes
What are diploid and haploid cells?
Diploid - contains both chromosomes from the homologous pair
Haploid - contains 1 chromosome from the homologous pair
How does genetic mutation affect enzyme function?
A change in the base sequence means a different amino acid sequence
This changes the active site, meaning the substrate won’t fit and the enzyme doesn’t function
Although, the base may still code for the same amino acid, and not all changes affect amino acids and the enzyme still functions
