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Cellular Processes
THE CELL IN ITS
ENVIRONMENT
1. How do small
substances move into and
out of the cell?
Diffusion
Osmosis
Active
Transport
2. What is diffusion?
Main
method by which small
molecules move across the
cell.
Molecules move from areas
of higher concentration to
an area of lower
concentration.
3. What causes
diffusion?
Molecules
will spread out
and bump into one
another until they are
spread evenly throughout
the environment.
4. How do single celled
organisms get oxygen from
water?
 More
oxygen molecules are outside
the cell (higher concentration of
oxygen) in the water.
 Oxygen diffuses from areas of
higher concentration (water) to
areas of lower concentration (inside
5. Predicting . . .What
would happen if the
concentration of oxygen
were higher inside the
cell than outside?
6. What is osmosis?
Diffusion
of water
molecules through a
selectively permeable
membrane.
NORMAL
High Conc of
H2O outside
(H2O enters)
& cell swells
High Conc of
H2O inside
(H2O exits) &
cell shrinks
7. What are the Effects
of Osmosis on Cells?
8. What is passive
transport?
For
a cell, moving materials
through the cell membrane
by diffusion and osmosis is
like cycling down hill.
It
does not require much
energy.
9. What is active
transport?
Using
cellular energy to move
materials through a cell
membrane.
–Ex: Cell would use when they
need to take in nutrients that has
a higher concentration inside the
cell.
10. What are transport
proteins?
Used
in active transport
– proteins “pick up”
molecules outside the
cell and carry them in,
using energy.
11. What happens when the
particles are too big?
Diffusion,
passive
transport, and active
transport do not work as
well.
The cell membrane relies
on endocytosis and
exocytosis.
12. What is endocytosis?
1.
Cell comes in contact
with a particle
2. Cell membrane wraps
around particle.
3. Once totally surrounded
a vesicle pinches off.
13. What is exocytosis?
1.
Large particles leaving cell
are packaged in vesicles.
2. Vesicle travels to the
membrane and fuses with it.
3. Cell releases particles into
the environment.
SOURCES OF ENERGY
1. How is the sun related to a
cell’s energy?
 The
sun supplies energy for most
living things directly or indirectly.
–Plants use energy from the sun to
make food.
–A giraffe obtains energy by eating
the grass.
–The lion obtains energy by feeding
on the giraffe.
2. What is photosynthesis?
 Photosynthesis
– process by which
a cell captures energy in sunlight
and uses it to make food.
–Autotrophs – organism that makes
its own food
–Heterotroph – organism that
cannot make its own food (usually
get food by eating other
organisms.)
Autotroph
Heterotroph
3. What happens during
photosynthesis?
Plants
use energy from the
sun to convert carbon
dioxide and water into
oxygen and sugars.
4. What are the two stages of
photosynthesis?
 As
related to baking a cake:
1.) Capturing the sun’s energy
(combine ingredients to make the
batter)
2.) Using energy to make food
(bake the batter)
5. What is the first stage?
Capturing the energy in
sunlight:
1. ) Occurs mostly in the
leaves
2.) Involves the chlorophyll in
the chloroplasts
3.) Chlorophyll captures light
energy and uses it to power
the second stage.
 Using
6. What is stage 2?
energy to make food –
–Cell needs water and carbon dioxide
–Carbon dioxide enters cell through
small openings under the leaves
(stomata)
–Water travels through plant’s stems to
leaves
–Once in the leaves – carbon dioxide
and water move into the chloroplasts.
6. Stage 2 continued . . .
 Inside
the chloroplasts – water and
carbon dioxide undergo a chemical
reactions
–One product is a sugar (carb) –
cell can use energy for various
functions
–The other product is oxygen
which exists the leaf through the
stomata.
PHOTOSYNTHESIS EQUATION
LIGHT
Carbon Dioxide
Water
Glucose
(sugar)
oxygen
7. How do you get energy from
respiration?
This
is the process by which
cells obtain energy from
glucose (sugar).
During respiration, cells break
down stored sugar and
release the energy it contains.
8. What are the two stages
of respiration?
Stage
1– Happens in cytoplasm
–Glucose broken down into
smaller molecules
–Releases small amount of
energy
Stage
2–
–Happens in the
mitochondria
–Small molecules broken
into smaller molecules
–Requires oxygen and
releases lots of energy
9. What are the products of
respiration?
 Energy
is released
 Carbon dioxide and water diffuse out
of cell
–* When you breathe in you get
oxygen (needed for respiration)
when you breathe you release
carbon dioxide and water (products
of respiration)
Respiration Equation
C6H12O6 + 6O2  6CO2 + 6H2O + energy
CELL DIVISION
1. What is the cell cycle?
Begins
when cell is formed and
ends when the cell divides and
forms new cells.
Before division, the cell must make
a copy of its DNA.
DNA of cell is organized in
chromosomes – copying them
helps ensures cell survival.
2. How do you make
more prokaryotic cells?
Not complex
Binary Division – “splitting
into two parts”
Each of the resulting cells
contains one copy of DNA.
3. How many chromosomes do
humans have?
Humans
have 46
23 pairs of homologous
chromosomes – (similar
chromosomes)
3. How do you make more
eukaryotic cells?
3
main stages
 STAGE 1 (Interphase)
–1. Cell grows and copies (DNA)
organelles and chromosomes.
Chromosomes are duplicated
– known as chromatids –
held together by a
centromere.
Chromatids
Centromere
 Second
Stage
–1. Chromatids separate through
mitosis.
–2. Mitosis ensures that each new
cell receives a copy of each
chromosome.
 Third Stage
–Cell divides and produces two cells
that are identical to the original cell.