module 2 - 6.4 organisation and specialisation of specialised cells & 6.5 stem cells Flashcards
what happens to cells in multicellular organisms for them to become specialised cells?
differentiation
what are the levels of organisation in multicellular organisms?
- specialised cells
- tissues
- organs
- organ systems
- organism
what are tissues?
collection of 1 or more types of specialised cells, tissue is adapted to perform particular function
what are organs?
a collection of tissues that are adapted to perform a particular function
what are organ systems?
a collection of organs that are adapted to perform a major function
what is the process of making specialised/ differentiated cells called?
differentiation
what do all animal, plant and fungal cells begin as?
undifferentiated cells - potential to differentiate into any specialised cells
what are undifferentiated cells called?
stem cells
what are body cells?
all cells in the body except gametes
what do all specialised cells have in common?
they have the same genome as the stem cells
why do all specialised cells have the same genome as the stem cells?
because they’re produced by mitosis, so some genes are switched on and some off
what can stem cells go through?
cell division
why may stem cells go through cell division many times?
to give rise to whole lineages of specialised cells
what are stem cells the source of?
new cells for growth, repair and changes to the body plan
how controlled is stem cell division?
strictly (come dancing)
what is potency?
ability of a stem cell to differentiate into specialised cells
what is a totipotent stem cell?
a stem cell that can differentiate into any specialised cell
what is a pluripotent stem cell?
stem cell that differentiates into all tissue types (not into extra-embryonic tissues)
what is a multipotent stem cell?
a stem cell that can only differentiate into the range of specialised cells found in a tissue
what type of cell is a zygote?
totipotent stem cell
what is a blastocyst?
a sack of human cells that forms in early pregnancy
when the human embryo is a blastocyst, what are the cells and why?
cells are pluripotent because they can form 3 germ layers
what are the 3 germ layers?
- endoderm
- mesoderm
- ectoderm
what is the endoderm layer used for?
- interior stomach lining
- gastrointestinal tract
- lungs
what is the mesoderm layer used for?
- muscle
- bone
- blood
- urogenital
what is the ectoderm layer used for?
- epidermal tissues
- nervous system
where are plant stem cells found?
meristems or meristematic tissue
where are the meristems/ meristematic tissue?
- shoot and root tips where growth by cell division occurs
- also found in vascular bundles between xylem and phloem tissue
what is the area called between the xylem and phloem tissue where meristems can be found?
VASCULAR CAMBIUM
where do animal stem cells come from?
- embryonic stem cells
- tissue or adult stem cells (located in specific areas after birth)
