Transcript What happens to cells when an egg meets a sperm, then turns into

What happens to cells when an
egg meets a sperm, then turns
into an embryo and finally a
fetus……….
Embryological Development
During embryological
development the unspecialised
cells of the early embryo
differentiate into cells with
specialised functions.
Learning Outcomes
• Explain differentiation in human cells
• Give the term for unspecialised of cells and
the process of differentiation
• Explain how proteins can be expressed
differently
What is a stem cell?
Stem cells are relatively unspecialised cells that
can continue to divide and can differentiate into
specialised cells of one or more types.
stem cell
SELF-RENEWAL
(copying)
REPRODUCE
DIFFERENTIATION
(specializing)
stem cell
specialized cell
e.g. muscle cell, nerve cell
Differentiation
In the very early embryo, embryonic stem
cells differentiate into all the cell types that
make up the organism.
Tissue (adult) stem cells replenish
differentiated cells that need to be
replaced and give rise to a more limited
range of cell types.
Bone Marrow …. Blood Cells
NK cell
T cell
B cell
dendritic cell
platelets
bone marrow
megakaryocyte
erythrocytes
macrophage
neutrophil
eosinophil
basophil
specialized cells
committed progenitors
Tissue (adult)
stem cells in the
red bone marrow
give rise to red
blood cells,
platelets and the
various forms of
phagocytes and
lymphocytes.
Gene Expression ….
Once a cell becomes differentiated it only
expresses the genes that produce the proteins
characteristic for that type of cell.
Pancreas
cell
Eye lens
cell
(embryo)
Key:
Active
gene
Nerve
cell
Crystallin
Glycolysis
enzyme genes gene
Insulin
gene
Hemoglobin
gene
Inactive
gene
Compare and Contrast .....
Embryonic Stem Adult Stem
Cells
Cells
Found / Location
Gene Expression
Differentiation
into cells
Somatic Cells
Somatic cells form different types of body
tissue.
Epithelial cells cover the body surface and
line body cavities, connective tissue includes
blood, bone and cartilage cells, muscle cells
form muscle tissue and nerve cells form
nervous tissue.
Somatic Cells
The body organs are formed from a variety of
these tissues.
During cell division the nucleus of a somatic
cell divides by mitosis to maintain the diploid
chromosome number. Diploid cells have 23
pairs of homologous chromosomes.
Modelling Mitosis!
Delightful Donuts .....
Put these pictures in order ...
Review 1. Name 3 different types of differentiated
tissue derived from somatic cells in addition
to connective tissue
2. What is the difference between haploid and
diploid?
3. What is a germline cell?
4. Briefly describe how a diploid germline cell
produces haploid gametes
5. Which type of cell (somatic or germline) is a
mutation not passed on to the members of
the next generation?