Cells Structures and
Functions
1.1.1
Summarize the structure and function of organelles in eukaryotic cells (including: the
nucleus, plasma membrane, cell wall, mitochondria, vacuoles, chloroplasts, and
ribosomes)
Explain ways that these organelles interact with each other to perform the function of
the cell.
What is a cell?
• A cell is the basic structural and
functional unit of life.
• All organisms are composed of
cells.
•
•
Some organisms are unicellular.
Other organisms are multicellular.
Is Plankton Unicellular of
Multicellular?
Two Types of Cells
1. Prokaryotic Cells (“prior to a nucleus”) are all
bacteria cells.
* They do not have a nucleus.
* They lack membrane-bound
organelles.
2. Eukaryotic Cells (“true nucleus”) are protists,
fungi, plants, animals
* they have a nucleus and MBO’s.
nucleus
(( •
Membrane-bound
organelle found in
eukaryotic cells.
• Contains DNA in
chromosomes.
• Pores are found in
nuclear membrane.
Why does the cell need a
Nucleus?
Directs cell activity through protein
synthesis.
DNA transcribes mRNA.
Structure vs. Function
Pores in nuclear membrane allow mRNA to
pass through to the ribosomes in the
cytoplasm for protein synthesis.
DNA in segments called genes are found in
chromosomes.
Nucleolus in nucleus produces the two
ribosome subunits.
Interaction of cell Organelles
Nucleus produces the mRNA which together
with the ribosome translate the DNA code
into polypeptide chains.
Nucleus is dependent on ATP production
from mitochondria. ATP is energy source for
DNA replication and transcription.
Plasma Membrane
• Plasma membrane is
a phospholipid
bilayer.
Plasma Membrane:
Description of Function
The plasma membrane of a cell is a
selectively permeable membrane. It
maintains chemical homeostasis.
The proteins help in cell signaling between
cells.
Plasma Membrane: Relationship
of Structure to Function
•
The phospholipids will block non-lipid
soluble(will not dissolve) molecules as well
as large molecules.
•
proteins act as carrier proteins and protein
channels
Plasma Membrane:
Interaction of Cell Organelles
•
Plasma membrane is the gateway for
absorption as well as secretion and excretion
of chemicals.
•
Cell signals via the plasma membrane may
ultimately control organelle function
Cell Wall
Cellulose fibers and Glycoproteins
Cell Wall: Description of
Function
•
Mechanical support yet plastic.
•
Protects cell from bursting under high turgor
pressure.
•
Protects cells from insects and pathogens
Cell Wall: Relationship of
Structure to Function
Cellulose microfibers provide strength.
Plasmodesmata are channels which connect
plant cells to each other.
Cell Wall: Interaction of Cell
Organelles
•
Cell walls protect the plasma membrane bound
components.
Mitochondria
• Mitochondria have
an inner and outer
membrane.
• The inner
membrane is folded
Mitochondria – Description
of Function
Mitochondria function in the process of aerobic
cellular respiration. They produce ATP energy for
the cell.
Mitochondria – Relationship
of Structure to Function
The increased surface area because of the folded
inner membrane gives more space for cellular
respiration.
Mitochondria - Interaction of
Cell Organelles
ATP is produced by mitochondria to fuel cell
work for other organelles.
What do you think?
What part of the body needs the most mitochondria?
Chloroplasts
• Small green
organelles.
Consist of stacks
(grana) of
membrane-bound
sacs.
• Chloroplasts have their own DNA which
looks like bacterial DNA.
Chloroplasts – Description of
Function
Has green pigment (chlorophyll) which absorbs light
energy for photosynthesis
Chloroplasts – Relationship
of Structure to Function
Membranous sacs provide large surface area for
photosynthesis reactions.
Chloroplasts – Interaction of
Cell Organelles
Some glucose produced by photosynthesis is used
by plant cell mitochondria to produce ATP.
What does photosynthesis and
cellular respiration have in
common?
Vacuoles
• Small (animals)
membrane bound
organelles. Large
in plants.
Vacuoles – Description of
Function
Storage of water or food
Maintains turgor pressure in plant cells.
Isolates harmful substances
Vacuoles – Interaction of
Cell Organelles
Large water vacuoles in plant cells maintain
turgor pressure.
Ribosome
• One small subunit and one large subunit,
both consisting of rRNA and proteins.
• Not membrane bound.
Ribosomes – Description of
Function
Integrates mRNA with tRNA to translate the
DNA code into a specific protein.
Ribosomes – Relationship of
Structure to Function
mRNA moves between the large and small
subunit.
There is an opening for growing polypeptide
to leave ribosome.
Ribosomes – Interaction of
Cell Organelles
Ribosome interacts with mRNA information
from the nucleus to form proteins.
Proteins are important for all cell organelles
(structure, hormones, enzymes)
Are you a
Prokaryote or a
Eukaryote?