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
optimum temperature
enzymes working at their best
e.g 37 degrees C in a human
why does higher temperature increase reaction?
goves molecules more energy so they collide more often
What happens at high temperature with enzymes
denature-
enzymes are made out of protiens
protiens are broken down by heat
40*C cupwards destroys the enzyme
What happens to enzymes in extremes of pH
affects structure of enzyme molecules and changes the shape of its active sight so substrate will not fit in that well
Optimum pH
pH at enzymes work best with
cell respiration
breaking down of food molecules to release the stored chemical energy
where does respiration happen
in all cells of our body
What is oxygen used to do in respiration?
oxidise foods
main food oxidised is glucose
What does glucose contain
stored chemical energy that can be converted into other forms that the cells can use
Chemical energy is used for
contraction of muscles
active transport of molecules + ions
building large molecules such as protiens
cell division
Aerobic (later steps)
happen in the mitochondria
anaerobic respiration
glucose is not completely broken down
less energy is released
Advantages of anaerobic respiration
it can occure when oxygen is in short supply
e.g. yeast or muscle cells
anaerobic equation for yeat
glucose -> ethanol + carbon dioxide
anaerobic equation for muscle cells
glucose -> lactic acid
lactic acid
substance glucose is broken down into
Why does person rest after anaerobic repiration
to oxidise the lactic acid FULLY
oxygen debt
volume of oxygen needed to COMPLETELY oxidise the lactic acid during anaerobic respiration
diffusion
happens when a substance is more concentrated in one place than the other
cell membrane is permiable to e.g. CO2 so there is a NET movement
diffusion of oxygen
opposite of CO2
Respiration uses O2 so net movement of O2 into cell by diffusion
Why does diffusion happen
Kinetic energy of the particles
Active transport
goes against the concentration gradient
the cell uses energy from respiration to take up the particles “pumping” it
What are the “pumps” made of?
large protien molecules located in the cell membrane
active transport in humans
small intestine->
some glucose is absorbed into the cells lining the intestine by active transport
active transport in plants
roots
osmosis
water moving accross cell membrane
Partially permiable
when does osmosis happen?
when the total concetration of all substances inside and out is different
water will move across the membrane from the more dilute soloution to the more concentrated one (obeys law of diffusion)
rate of diffusion increased by
steep concentration gradient
high temp
large surface area
diffusion examples
alvioli
villi (of the mall intestine)
spingy mesophyll
zygote
multicelular organism beginning life as an egg
tissues
cells with familiar functions
organ
collection of several tissues carrying out a particular function
organ system
jobs carried out by several different organs working togethor
main systems in human body
digestive
respiratory
circulatory
excretory
nervous
endocrine
reproductive
eukaryotes
complex: animal + plant cells
prokaryote
single celled organism - prokrayotic cell
