Chapter 1: Life processes Flashcards
excrete
get rid of toxic waste products
respond to stimuli
sensitive to changes in their surroundings
control
internal conditions
cytoplasm
living materian that makes up a cell
structures of these
organelles
nucleus
controls activities of cells
contains chromosomes which carry genes
genes
control the activities in the cell by determining which protiens the cell can make
Enzymes
control chemical reactions that go on in the cytoplasm
cell surface membrane
not a complete barrier
selectively permiable
controls what substances go in + out
metabolic reactors
chemical reactors taking place in a cell
mitochondria
carry out some reactions of respiration
Most energy from respiration is released in mitochondria
cell wall
non living
made out of cellulos
keeps its shape
freely permiable
how do plant cells get support
plant cells absorb water, producing internal pressure which pulses against other cells of the plant
vacuole
permanent feature
filled with cell sap - dissolved sugars, mineral ions + other solutes
chloroplasts
absorb light energy to make food in photosynthesis
contain chlorophyll which makes them green
Enzymes (protiens)
biological catylists
Catalyst
speeds up a reaction without being used up itself
nucleus contains genes, which control production of enzymes which catalyse reactions in the cytoplasm
Why enzymes are needed
temperatures in organisms are low, without catalysts most reactions would be too slow for life to go on
substrate
the molecule an enzyme acts on
Each enzyme has a small area on its surface
active site
enzyme (steps)
substrate attaches to the active sight
reaction takes place, then products are formed
What happens to energy when substrate joins with active site
Lowers the energy needed for reaction to start, allowing products to be formed more easily
factors affecting enzymes
pH of surroundings
Concentration of enzyme or substrate
temperature