The Cellular Structure of Eukaryotic Cells

Chapter 5

You need your microbiology You need your microbiology textbook!textbook!

You need your microbiology You need your microbiology textbook!textbook!

Objectives

• Identify the structure of a typical cell

• Define the function of each part of the eukaryotic animal cell

• Describe the processes that transport materials in and out of a cell

Cells

• Basic structural unit of living things• Eukaryotes

– Cells that have true nucleus held by a nuclear membrane. Has chromosomes and divides by mitosis.

• Prokaryotes– Unicellular organism lacking a true nucleus

and nuclear membrane. Its genetic material consists of a single loop of DNA and no chromosomes

Cells

• Cytologists specialize in the pathology of the cell, whose changes in internal structures give important clues as to the cause or source of disease

Cells

• Organelles – specialized structures found with the cytoplasm of cells, each with a specific function

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Cell Structure

• Nucleus– Control center for all cell activity. Contains

the chromosomes and DNA.

• Cell Membrane– A thin layer of plasma-like material that

surrounds the cytoplasm and the organelles. It is located between the cell wall and the protoplasm of the cell and allows molecules to pass in and out of the cell

Cell Membrane

• Cytoplasm– Gel-like protoplasm of a cell that surrounds

the nucleus. It is bound by the cell membrane and holds the organelles in place

• Nucleolus (and Ribosomes)– A rounded body in the nucleus of most cells

that is the site of ribosomal RNA synthesis

Cell Structure

• Endoplasmic Reticulum– Network of folded membranes in the

cytoplasm of a cell that transport materials throughout the cell

• Mitochondria– Rod-shaped organelle of cells that is

responsible for cellular respiration and energy production

Cell Structure

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Cell Structure

• The Golgi Apparatus– Packages and wraps proteins for export out of

the cell

• Lysosomes– Aids in the digestion of proteins by secreting

digestive enzymes

• Pinocytic Vesicles– Pockets or folds in the cell membrane that

allow large molecules such as proteins and lipids to be taken into the cell

Cell Structure

Movement across the cell membranes

• Diffusion

• Osmosis

• Filtration

• Active transport

• Phagocytosis

• Pinocytosis

An active process that requires an energy source

A passive process – requires no energy to

function

Diffusion

• Process of spreading out or movement of molecules through a substance. The larger the molecules the slower the movement.

Osmosis

• Passage of a solvent’s molecules through a selective permeable membrane from a solution of lesser solute concentration to a solution of greater solute concentration

Filtration

• Process of a fluid passing through a filter

Active transport

• When cells must move materials in an opposite direction - against a concentration gradient. It requires Energy

• Phagocytosis– "cell eating" - extensions off cytoplasm

surround a particle and package it within a food vacuole and then the cell engulfs it.

• Pinocytosis– the process of taking up liquid from the

surrounding environment. Tiny pockets form along the membrane, fill with liquid, and pinch off

Active transport