Cell Structure & Function

Definition of Cell A cell is the smallest unit that is capable of performing life functions.

Cell Theory: Importance of Cells 1)All living things are made up of cells 2) Cells are the smallest units in all living things 3) All cells come from existing cells through cell division

Examples of Cells Amoeba Proteus Plant Stem Red Blood Cell Nerve Cell Bacteria

Two Types of Cells Prokaryotic Eukaryotic

Prokaryotic Single-celled organisms that DO NOT HAVE NUCLEUS DNA/RNA floating freely inside cell (circular loop of DNA) Do not have structures surrounded by membranes Few internal structures Ex: Bacteria

Parts of a Prokaryotic Cell Nucleoid – Area where DNA or RNA is located. Not enclosed in a membrane like a nucleus. Ribosomes – Small structures that use DNA or RNA instructions to produce proteins. Pili – Hollow, hair-like structures that can be used to exchange genes. Flagella – Spin to produce movement. Cell membrane – Controls what leaves or enters the cell

Eukaryotic Contain organelles surrounded by membranes HAS A NUCLEUS DNA in chains Animals, plants, protists, fungus PlantAnimal

DIAGRAM ANSWERS Animal 1)Centrioles 2)Plasma Membrane 3)Peroxisomes 4)Mitochondria 5)Cytoskeleton 6)Lysosomes 7)Smooth Endoplasmic Reticulum 8) Golgi Apparatus 9) Vesicles 10) Ribosomes 11) Rough Endoplasmic Reticulum 12) Nucleus 13) Nucleolus 14) DNA

DIAGRAM ANSWERS Plant Cell 1)Smooth ER 2)Plasmodesmata 3)Mitochondria 4)Cell wall 5)Cell membrane 6)Cytoskeleton 7)Perioxisomes 8)Vacuole 9)Chloroplast 10)Ribosome 11)Rough ER 12)Golgi Apparatus 13)Vesicles 14)Nucleolus 15)Nucleus 16)DNA

Comparison of Eukaryotes and Prokaryotes

Cell Parts Organelles

Surrounding the Cell

Cell Membrane Phospholipid double layer Outer membrane of cell that controls movement in and out of the cell

Cell Wall Most commonly found in plant cells & bacteria Supports & protects cells

“Typical” Animal Cell /~ acarpi/NSC/images/cell.gif

“Typical” Plant Cell

Inside the Cell

Nucleus Contains genetic material - DNA Directs cell activities Separated from cytoplasm by nuclear membrane

Nuclear Membrane Surrounds nucleus Is made of two layers Openings allow material to enter and leave nucleus

Chromosomes In the nucleus, DNA is packaged into structures called chromosomes Made of DNA Contain instructions for traits & characteristics

Nucleolus Inside nucleus, is a region called the nucleolus Contains RNA to build proteins

Organelles that build proteins Ribosomes Endoplasmic Reticulum Golgi Apparatus

Ribosomes Proteins are made (synthesized) on Ribosomes Each cell contains thousands Found floating throughout the cell or attached to the Endoplasmic Reticulum

Endoplasmic Reticulum Function: Produce proteins needed by the cell Structure: huge membrane that is connected to the nuclear membrane. There are two distinct regions of ER: –Smooth ER, which lacks ribosomes, breaks down toxins –Rough ER, with ribosomes studding its surface

Golgi Bodies Protein 'packaging plant’ Flattened membrane sacs with vesicles Moves, sorts, packages, transports materials within cell Move materials out of the cell A typical path for a protein produced by the cell: Rough ER → Golgi → Cell membrane → Released by cell

Organelles that Store, Clean up, and Support Lysosomes Vacuoles

Lysosome Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Lysosomes break down old organelles Cell breaks down if lysosome explodes

Vacuoles Membrane-bound sacs for storage, digestion, and waste removal Contains water solution Help plants maintain shape

Organelles that Capture and Release Energy Mitochondria Chloroplasts All life requires energy Organisms either can get their energy from sunlight via photosynthesis, or by eating other organisms via cell respiration Photosynthesis occurs in chloroplasts. Cell respiration occurs in mitochondria.

Mitochondria Mitochondria are the power houses of the cell. They convert the chemical energy stored in food into smaller molecules for the cell to use: What is the process??? Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates ml

Chloroplast Usually found in plant cells Contains green chlorophyll Where photosynthesis takes place  FUNCTION: capture light energy and convert it to chemical energy

Cytoplasm Gel-like mixture Surrounded by cell membrane Contains hereditary material

Cell Specialization Not all cells are similar looking. Cells may have different sizes, structure, and function. Many cells have a specialized structure that enables them to better carry out their specific function.