Introduction to the Cell Chapter 7.1

Introduction to the Cell Cell- smallest unit of matter that can carry on all of the processes of life Hooke and Leeuwenhoek used microscopes to see first images of cells in the ’s.

The Cell Theory… a. All living things are composed of cells b. Cells are the basic units of structure and function in an organism (smallest living unit). c. Cells come only from the reproduction of existing cells (cells come from cells).

Cells Size… Limited in size because of surface to area ratio –If a cell gets too big the nutrients and wastes do not have enough surface area to come into / out of the cell

Shape… A cells shape is usually associated with its job.

Internal Organization… Cells contain many organelles –Def: cell component that performs specific functions for the cell Like mini organs –Cell membranes surround cell and decides what goes in and out of the cell. –Nucleus contains genetic information (DNA), which controls the cell.

Eukaryotic vs. Prokaryotic Eukaryotic –Cell that has membrane bound organelles –More complex –Plant and animal cells -YOU are a eukaryote! Prokaryotic –Has membrane around entire cell –No organelles –No nucleus –bacteria

Eukaryotic vs. Prokaryotic

Bill Nye: Discovery of Cells

Organelles Inside the Eukaryotic Cell 7.2

Cell Membrane The lipid bilayer that surrounds the cell

Cell Membrane cont. Controls what enters/leaves the cell Selectively permeable – allows some substances to enter while not allowing others to enter Sometimes have proteins integrated into the layer, some are on either side of the bilayer

All cells have: Cytoplasm-a jelly like substance that fills the cell within the cell membrane. Ribosomes- the cellular structure where proteins are made.

Nucleus Contains DNA, hereditary info. Surrounded by the nuclear membrane Also has a nucleolus where ribosomes are made. The cell’s “brain.”

Mitochondria Site of chemical reactions that produce ATP (energy). Have folded center to allow for more surface area for production of ATP Have their own DNA Many of them in the cell

Ribosomes Numerous; some are free floating others are attached to Endoplasmic Reticulum Play a large role in the production of proteins

Endoplasmic Reticulum Act as highway for proteins and other substances, has many different channels Rough ER – ribosomes make proteins, ER ships them off Smooth ER – makes steroids, regulates calcium, and breaks down toxins

Lysosome Uses enzymes to digest/break down organic compounds, old cell parts and other materials

Golgi Apparatus Processes and packages cells proteins

Cytoskeleton ~ Provides support and allows movement like a human’s skeleton.

Cilia and Flagella Cilia Found on outside of the cell Aid in movement Hair-like structures Cilia are short and come in large numbers Flagella Found on out side of the cell Aid in movement Hair-like structures Flagella usually come in 1-3.

Plant vs. Animal Cells Both plants and animals have more complex eukaryotic cells. However there are some differences in there structure.

Plant Cells… Have cell wall for structural support- like plant bones Has large vacuoles for storage of water and toxins Have Chloroplasts that convert light into chemical energy

Animal Cells No cell wall, just a cell membrane. No chloroplasts. No vacuole.

Levels of Organization From Cells to Organisms 7.3

Multicellular Organization Cell Tissue Organ Organ System Organisms

Multicellular Organization Cell=The smallest unit of life. Tissue= A group of similar cells that are working together. Examples: Muscle tissue or bone tissue. Organ= Similar tissues organized into a structure with a specific function. Examples: Heart, bones, liver.

Multicellular Organization Organ system- Various organs working together to carry out a major body function. Examples: digestive system, urinary system, reproductive system. Organism-Any living thing that can carry out life processes independently.