Cells
- Created by: Maryah_Jasm
- Created on: 05-09-17 21:11
We are multicellular organisms - made of approx 10 trilion cells
each cell contain same genetic info/code
we have different cell types
all start life as single fertilised cell (zygote) - genetic information is stored in nucleus of first cell
as zygote divides cell structures become different
during development cells all become defined part of organism - differentiation
differentiation occurs in developing foetus after sixteen-cell stage - each cell has chemical signals that cause certain genes to be switch on/off
in large organisms, similar cells are grouped into tissues which carry out a single function - the same genes inside the nucleus of each tissue are switched on/off
muscle cells form muscle tissues which contract and relax to eable movement
certain cells differentiate into cells which secrete enzymes and hormones - these form glandular tissue
skin - epethelial tissue
collection of tissues which work togeher to carry out same fucntion - organ
e.g. stomach: muscular tissue - to churn up food. Glandular tissues - secete pepsin (protease enzyme needed to start digestion of protein). Epethelial tissue - inside and outside of stomach.
organ system- collection of organs which carry out a function
if the wrong genes are switched on/off during diferentiation, problems can arise
All living things…
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