Key Area 1 Flashcards
Which 2 types of human cells are there?
Somatic and Germline
what are somatic cells?
any cell in the body other than those involved in reproduction
give 3 examples of a somatic cell
bone, lung, brain, blood, heart muscle, skeletal muscle, pancreatic, kidney, liver
how to somatic cells divide?
mitosis
what does mitosis allow to be maintained?
diploid chromosome compliment
how many pairs of homologous chromosomes do diploid cells have?
23
where are germline cells found?
reproductive organs
what are germline cells
stem cells that divide to form gametes
give 2 examples of a gamete
sperm ova
how do germline cells divide?
mitosis and meiosis
what happens when germline cells divide by mitosis?
more germline stem cells are produced
what happens when germline cells divide by meiosis?
haploid gametes are produced
which 2 divisions must a cell undergo in meiosis
separating homologous chromosomes
separating chromatids
how many single chromosomes do haploid gametes have?
23
why do cells need different genes to be expressed?
genes carry the code to make proteins and different proteins are needed for different cells
what are housekeeping genes?
genes required by every cell to maintain basic functions and structures
give 2 examples of genes only needed by specific cells
pancreatic cells need genes to produce insulin and glucagon
stomach cells need genes to produce pepsin for digestion
describe gene expression
all cells contain all genes ( in somatic cells ) but only some are required for each cell. the cell can turn on (express) genes that are required and turn off any that are not
what is cellular differentiation?
the process by which a cell expresses certain genes to produce proteins needed for that type of cell.
What does cellular differentiation allow?
allows cells to go from an unspecialised stem cell to a cell which can carry out a specialised function
do all stem cells differentiate?
no, some will self renew
describe cellular differentiation in an early embryo
cells can differentiate into all cell types because all genes can be expressed
what term is used to describe embryonic stem cells?
pluripotent
what are tissue stem cells involved in?
growth, repair and renewal of cells found in that tissue
what can tissue stem cells differentiate into?
all types of cell found in a particular type of tissue
why can tissue stem cells only differentiate into cells found in a particular type of tissue
only some genes in tissue stem cells can be expressed
what can blood stem cells located in bone marrow differentiate into?
red blood cells
platelets
phagocytes
lymphocytes
what term is used to describe tissue stem cells?
multi potent
why are embryonic stem cells used in research?
the embryo can self renew under the right conditions
give 2 examples of therapeutic uses of stem cells
corneal repair
regeneration of damaged skin
give 2 examples of research uses of stem cells
provides information on cell growth, differentiation and gene regulation work
study how diseases develop or can be used in drug testing
what are the ethical issues surrounding embryonic stem cell use?
- offers effective treatment of disease and injury
- involves destruction of embryos and potential life
what signals do cells constantly send?
regulatory signals both internally and externally
when are cell signals sent and detected?
if the cell’s DNA becomes damaged
what happens after the cell sends signals and the signals are detected?
action is taken to repair DNA damage
What happens to a cell if DNA damage cannot be repaired?
the cell will send another signal instructing apoptosis
what is apoptosis?
programmed cell death
what does apoptosis prevent?
the damaged cell undergoing mitosis
when does cancer occur?
when apoptosis fails and the cell does not die, instead, the damaged cell divides excessively
what does the failure of apoptosis result in
a mass of abnormal cells ( tumour ) forming
what happens if tumours fail to attach to each other?
they can spread around the body and cause secondary tumours to form
