Cells Structures and Functions

1.1.1Summarize 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

OrganellesATP 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?