The Cell: Cell structure and the organelles

What is a cell? A CELL is the smallest unit that is capable of performing life functions.

Comparing Cells: Cells come in many SIZES. A cells shape might tell you something about its FUNCTION.

Cell Types: Scientists have found that cells can be separated into TWO groups. 1.) Cells without membrane-bound structures are called PROKARYOTIC CELLS. They are only found in one-celled organisms such as bacteria. 2.) Cells with membrane-bound structures are called EUKARYOTIC CELLS. Animal and plant cells are eukaryotic cells.

Eukaryotic Cells

Prokaryotic Cells

Cell Organization: Each cell in your body has a specific FUNCTION.

Cell Wall: CELL WALLS are tough, rigid outer coverings that protect the cell and give it shape. Only PLANT CELLS contain a cell wall.

Cell Membrane: The protective layer around all cells is the CELL MEMBRANE Holds the cell together If cells have cell walls, the cell membrane is INSIDE of it. Regulates interactions between the cell and the environment Water is able to move freely into and out of the cell through the cell membrane Food particles and some molecules enter and waste products leave through the cell membrane

Cell Membrane cont.: The cell membrane is SEMI PERMEABLE, allowing some substances to pass into the cell and blocking others. It is composed of a double layer of the phospholipids and embedded proteins. It regulates interactions between the cell and the environment WATER is able to move freely into and out of the cell through the cell membrane.

Cell Membrane

Cytoplasm: CYTOPLASM is the jellylike material outside the cell nucleus in which the organelles are located. Most of the a cell’s LIFE PROCESSES occur in the cytoplasm. Throughout the cytoplasm is a framework called the CYTOSKELETON. Cytoskeleton helps the cell MAINTAIN OR CHANGE ITS SHAPE and enable some cells to move

CYTOPLASM cytoplasm

CYTOSKELETON CHIEF FUNCTIONS INCLUDE: movement of MATERIAL through the cell for stuff not diffusion or osmosis maintaining the SHAPE of the cell keeping the cell from getting SMASHED

CYTOSKELETON

Nucleus: The NUCLEUS directs all cell activities and is separated from the cytoplasm by a membrane. Materials enter and leave the nucleus through openings in this membrane. The nucleus contains the INSTRUCTION for everything the cell does. The instructions are found in DNA DNA is the chemical that contains the code for the cells structure and activities It specifies everything that is needed for the MAINTENANCE, FUNCTION, AND REPLICATION OF THE CELL.

Nucleus The “BRAIN” of the cell Controls all of the cellular activities DNA is inside the NUCLEOLUS

NUCLEOLUS The dark area in the NUCLEUS Like a TINY nucleus inside the nucleus.

Chromosomes: Are found inside the nucleus Carry the information that determines what traits a living thing will have

Protein: Takes part in nearly every CELL ACTIVITY Are apart of the cell membrane Cells make their proteins on small structures called RIBOSOMES

Ribosome: NOT membrane bound Some float freely in the CYTOPLASM Others are attached to the ENDOPLASMIC RETICULUM Made in the NUCLEOLUS

Endoplasmic reticulum: Also called the ER Extends from the nucleus to the cell membrane May be “rough” or “smooth”

Smooth ER vs. Rough ER

Endoplasmic Reticulum: Smooth ER Rough ER Has no attached RIBOSOMES Main function is TO COLLECT, MAINTAIN, AND TRANSPORT things Stores ions for the cell to keep nutrients balanced Has attached RIBOSOMES It has bumps all over it giving it a “ROUGH” appearance Makes proteins to be used in the cell

Golgi Bodies: Stacked, flattened membranes Like a loose stack of pancakes PACKAGING and DISTRIBUTION of materials to different parts of the cell

Energy-Processing Organelles: Cells require a continuous supply of ENERGY to process food, make new substances, eliminate wastes, and communicate with each other.

Chloroplasts: In some plant cells food is made in green organelles in the cytoplasm called CHLOROPLASTS Contains the green pigment CHLOROPHYLL, which gives many leaves and stems their green color Many cells, including animal cells, do not have chloroplasts for making food They must get food from their environment

Chloroplast

Mitochondria: Mito = Mighty / Power The POWER-HOUSE of the cell They break down food molecules so the cell has the ENERGY to live If a cell needs a lot of energy…it will have more mitochondria MITOCHONDRIA are organelles where energy is released from the breakdown of food into carbon dioxide and water.

Mitochondria

LYSOSOMES They combine with the food taken in by the cell The enzymes in the lysosome bond to food & digest it (acidic interior) Next…smaller molecules are released which are absorbed by the MITOCHONDRIA

From cell to organism: Cells in a MANY-CELLED organism do not work alone Each cell carries on its own life functions while depending in some way on other cells in the organism. A TISSUE is a group of similar cells that work together to do one job. Each cell in a tissue does its part to keep the tissue alive. Tissues are organized into organs An ORGAN is a structure made up of two or more different types of tissues that work together.

From cell to organism cont.: A group of organs working together to perform a certain function is an ORGAN SYSTEM. Example: Your heart is an organ made up of cardiac muscle tissue, nerve tissue, and blood tissues……… Your heart, arteries, veins, and capillaries make up your cardiovascular system.

The Organelles -nucleus -cytoplasm -nucleolus -cytoskeleton -cell membrane -vacuole -mitochondria -chloroplast -golgi Apparatus -centrioles -lysosomes -ribosomes -endoplasmic reticulum(ER) *Rough ER & Smooth ER