Lecture 15: HOW DO GENES MAKE A CELL? Flashcards
What is there within an individual?
Many different cell types
What must each cell do?
Respond to the environment, make and break molecules, generate energy and maintain itself
What are cells?
Very organised structures which contain different organelles. Dynamic and many different roles within
How much of a typical human cell is protein?
50%
How much of a typical human cell is lipids?
40%
How much of a typical human cell is carbohydrates?
10%
Where do building blocks of cells come from?
Plants (O2, CO2, light energy, water, minerals/nutrients in soil)
What are the building blocks of cells?
Carbon chains, sugars, amino acids, sugar and base
What do carbon chains form?
Lipids
What do sugars form?
Complex carbohydrates
What do amino acids form?
Proteins
What do sugar and bases form?
Nucleic acid (DNA and RNA)
What are the supramolecular assemblies?
Membranes, ribosomes and chromosomes
What are the organelles?
Nucleus, Golgi, ER and mitochondria
What is glycolysis?
Breakdown of glucose to pyruvate
What is needed for glycolysis?
All enzymes needed
What is the order of the central dogma?
DNA > transcription > RNA > Translation > protein
How is the central dogma regulated?
Transcription control, RNA processing and stability, translation control, protein processing, protein activity and stability
What does transcription control determines?
When and in what cells a gene is transcribed to produce mRNA
What is the first step in determining how many individual proteins are produced in a cell?
Transcription control
What does every cell have?
The same DNA and the same approximately 21,000 protein coding genes
How many genes are expressed in any cell type?
About 11,000 to 17,000
How many genes are expressed in all cells and needed for cellular function?
10,000
How many genes are unique to a specific cell type?
About 1,000 to 2,000
What do the unique genes do?
Make one cell type different from another
What is done with the rest of the genes?
They are expressed in some but not all cell types
What is transcription?
The process where a DNA sequence is copied (transcribed) into an RNA molecule
What happens to a gene when it is transcribed?
It is ‘turned on’ or ‘expressed’
Transcription is a …
key control point
How is transcription a key control point?
If a gene is transcribed, it can be used to make a protein and if a gens is not transcribed in a cell, it can’t be used to make a protein
How many base pairs do we have?
3,200,000,000
What are transcription factors?
Proteins that bind to a specific DNA sequence and control the rate of transcription (DNA to RNA)
What are the key elements of a gene?
The regulatory/promotor region and the transcribed region
Where is the regulatory/promoter region?
around 1000 to 2000 base pairs found before the start codon
What is the regulatory/promoter region?
The DNA sequence at which transcription factors bind and recruit RNA polymerase
What does the regulatory/promoter region determine?
How much a gene is transcribed
What does the regulatory/promoter region contain?
Short sequences that transcription factors bind to
What is the transcribed region?
Sequences of DNA that are copied into RNA (transcribed)
What is done with the transcribed RNA (pre-mRNA)?
It is processed so that it can be translated (intron sequences are removed by splicing)
When is a gene expressed?
When activator transcription factors are present and repressor transcription factors are absent
What do transcription factors do?
Bind to the promoter region and recruit RNA polymerase
What does having multiple transcription factors do?
Give precise control
What must cells be able to do?
Respond to the conditions outside the cell
How do the cells respond to conditions outside the cell?
By signalling molecules outside the cell binding to receptors on/in the cell and causing a change in activity of proteins inside the cell (signal transduction)
