3.8.2 Gene expression and cancer Flashcards
Totipotent stem cells are able to differentiate into..
any type of body cell
multicellular organisms are made up from…
many different types of specialised cells
specialised cells originated from..
stem cells
unspecialised cells that can develop into other cell types are called
stem cells
Two main sources of stem cells can be found..
in the embryo, adult tissues
these types of stem cells are only present in mammals in the first few divisions of the embryo
totipotent (very early embryo)
these types of stem cells are still found in the embryo but have lost their ability to develop into differentiate into placental cells
pluripotent
adult stem cells can be one of two types
- multipotent stem cells
2. unipotent stem cells
these types of stem cells can differentiate into a limited number of stem cells e.g. bone marrow cells can form RBC and WBC
multipotent stem cells
These types of stem cells can only differentiate into ONE type of cell
unipotent
Stem cells specialise because…
different genes are expressed (turned off and on)
All cells contain the same DNA - true or false?
true
Stem cells all contain the same genes - true or false?
true
Molecules which regulate the expression of genes are called..
transcription factors
Where do transcription factors bind to regulate gene expression?
upstream of the gene (promoter region)
What do transcription factors do to regulate gene expression?
encourage binding of RNA polymerase (turn on genes) or prevent RNA polymerase binding (turn off genes)
Where are transcription factors found?
nucleus
When a cell receives a signal to express a gene what does the transcription factor do?
moves from the cytoplasm to the nucleus
Specialised cells all look different - why?
they all express different genes and thus proteins - this determines the cells overall structure
Which stem cell can red blood cells originate from?
bone marrow stem cells
Transcription is when
DNA is copied into mRNA
Translation is when
mRNA is translated into a sequence of amino acids
what are cardiomyocytes?
heart cells
what can stem cells be used for?
treat diseases e.g. paralysis - replace damaged cells/tissues
benefits of using stem cells in medicine?
save life and improve quality of life for many people
iPS cells stands for?
induced pluripotent stem cells
What are iPS cells?
created in the lab - reprogramming adult stem cells to become pluripotent
What are the limitations with adult stem cells?
limited differentiation capacity - they are mulitpotent
Where do we source embryonic stem cells from?
embryos created in the lab from IVF
Embryonic stem cells are classified as one of twp types
- totipotent (very early embryo)
2. pluripotent (early embryo)
Issue surrounding embryonic stem cells?
- ethics surrounding the sourcing of the embryos (embryo will be destroyed)
In all cells which genes will be permanently expressed?
genes involved in respiration
All organisms develop from a fertilised egg - what is the scientific name for this?
zygote
Zygotes divide by what process?
Mitosis
Can specialised cells change into other cell types?
animals - no
plants - yes - shoots/roots
Name a hormone that can regulate transcription
oestrogen
What type of hormone is oestrogen?
steroid hormone
How can oestrogen enter the cell?
lipid soluble and diffused through the phospholipid bilayer
What does oestrogen bind to to regulate transcription?
a binding site/receptor site on the transcription factor
When oestrogen binds to the receptor on the transcription factor what happens?
The DNA binding site on the transcription factor is now able to bind to DNA (transcription activated)
Why is oestrogen able to bind the receptor on transcrption factor?
oestrogen has a complementary shape the the receptor
What property of oestrogen allows it to diffuse through the phospholipid bilayer?
lipid soluble
Who proposed the structure of DNA?
Watson and Crick
What is meant by epigenetics?
heritable changes in gene function without change the base sequence of DNA
What sort of environmental factors might influence phenotype?
stress, sunlight, chemical exposure, diet,
How is your DNA organised into chromosomes?
DNA wrapped around proteins called histones (forming chromatin)
DNA and histones are covered in chemicals known as ..
tags
Tags attached to the DNA and histones form a second layer known as..
the epigenome
What determines the shape of the DNA and histone complex?
epigenome