BIOMED 7 Flashcards
Genetics + genomics
How do cells look different?
Shape/size
Function
What is inside cell
- genetics makes this occur
How are the structure + function of specialised cells determined?
By the different proteins being expressed by the cell
What determines which proteins are expressed in a cell?
DNA: instructions for making different cell proteins, found in nucleus
What is DNA?
Full set of instructions for all 25,000 human body proteins
- but in any cell, only DNA instructions needed for that particular cell’s proteins are switched on, other DNA is silenced
What does DNA stand for?
Deoxyribonucleic acid
How does DNA exist?
Chromosomes in the nucleus
How many chromosomes do somatic (body) cells have?
46: 22 pairs + sex chromosomes (diploid, 2 of each)
Which body cells don’t have chromosomes?
Red blood cells (no nucleus)
How do gametes determine the DNA each person has?
23 chromosomes (haploid)
Fertilsation results in 1 diploid cell (zygote)
What is the structure of DNA?
Double helix
Biological molecule
Type of nucleic acid
How does DNA form a chromosome?
Condenses when cells about to divide
What is a chromatid?
Doubled/replicated chromosome (92)
What is the DNA code?
3 billion bases (4: A&T, G&C), make up the 46 chromosomes
- endless ways these can be arranged
What is the human genome project?
Mapped sequence of human genome, 3 bil human bases
What is RNA?
Ribonucleic acids
Exists as single strands
What are the 3 main functions of RNA in the cell?
Helps copy DNA instructions so proteins can be made
Helps build new proteins in cytoplasm
Forms ribosomes
What are the building blocks of proteins?
All made up of amino acids (20, combined in almost infinite ways to make large number of dif proteins needed)
How are proteins built up?
Primary structure: peptide
Secondary structure: eg helix, sheets (folded up)
Tertiary structure: eg active sit, enzymes
What is a gene?
part of a DNA molecule that codes for a protein
How many genes are there in humans?
20,000-25,000 spread across chromosomes
Does every cell carry all DNA?
Every cell carries all of DNA instructions
In one cell, only instructions (genes) for that cell’s proteins switched on
Each gene codes for a different protein
In humans, genes that code for proteins make up what % of our DNA?
2% Coding
98% Non-coding (regulates gene expression)
What does the genome consist of?
All of the DNA in any cell
- coding
- non-coding
- DNA in mitochondria
How are proteins made in cells?
Protein synthesis
Describe the process of protein synthesis
DNA- gene instruction in group of 3 bases (codon)
RNA- transcription: copies instruction
Ribosomes- translation: reads instruction and builds amino acids into correct order to make protein
How does the ribosome move along the mRNA to read the triplets?
Like a ball
What is the name for the flow of information DNA → RNA → protein?
Central dogma
Why is cell division needed in:
- childhood and adolescence?
- adulthood?
Grow
Renew + repair
What is the rate of cell division for GI epithelial cells?
Every 2-4 days
What is the rate of cell division for basal skin cells?
Every 10-30 days
What is the rate of cell division for brain cells?
Rarely, if ever
What is mitosis?
Cell division
2 daughter cells produced: genetically identical to parent
Diploid, 46 chromosomes (same number as parent)
What is asymmetric cell division?
Stem cells keep a copy of themselves when dividing, daughter cells have different properties
What is meiosis?
Making gametes from body cells
Cell division
4 daughter cells produced (haploid, 23 chromosomes)
Some crossing over of DNA, so every gamete is genetically different
What specific cells can make gametes?
Testes cells (diploid somatic) → sperm cells (haploid)
Ovary cells (diploid somatic) → ova/egg cells (haploid)
