Introduction to the Cell Learning Outcome B2 Introduction to the Cell

Cell Theory Modern Biology considers the cell theory one of its main ideas: The cell is the basic unit of life All organisms are composed of one or more cells All cells come from living things

Cell Theory Cells can be divided into two groups: Prokaryotic cells – organelles are not surrounded by a membrane. Example – bacteria Eukaryotic cells – organelles are surrounded by membranes. Example – multicellular organisms and some unicellular organisms

Prokaryotic Cell

Eukaryotic Cell

Bacteria Over 5000 different species and can be found everywhere on Earth. Can be harmful and helpful to humans Example – diseases Example – antibiotics Classified based on shape: Cocci – sphere-shaped Bacilli – rod-shaped Spirilla – spiral shaped

Cocci Bacteria

Bascilli Bacteria

Viruses Example – HIV, chicken pox, cold sores, flu Not considered to be living because they can only reproduce within a host. Do not have a nucleus or any other organelles. Only have a ring of DNA, so reproduction can occur.

Virus

Types of Cells There are two types of cells: plant animal

Composition of Cells Cells are made up of organelles. Organelle– is a structure within a cell that carries out functions that allow a cell to survive. Take up 5-30% of a cell , the rest of the cell is composed of water. Many organelles are covered by a membrane, which is a thing covering.

Types of Organelles Cell Membrane – a membrane that covers the entire cell, that controls and regulates what enters and exits the cell.

Types of Organelles Cytoplasm – is a jelly-like substance within the cell that contains organelles, water and other materials essential for life.

Types of Organelles Nucleus – is the control centre of the cell and it contains DNA (deoxyribonucleic acid), which is the hereditary material of an organism.

Types of Organelles Mitochondria – is an organelle that produces energy via cellular respiration. It takes energy from the food we eat (metabolism).

Types of Organelles Ribosomes – make proteins. Some ribosomes are attached to the endoplasmic reticulum, while some are floating in the cytoplasm.

Types of Organelles Endoplasmic Reticulum – is a network of folded membrane channels. Have a large surface are in a small space.

Types of Organelles Golgi Body (AKA – Golgi Apparatus) – is an organelle that sorts proteins an packs them into membrane-wrapped structures called vesicles.

Types of Organelles Vesicles – carry water, nutrients, and proteins into and out of the cell.

Types of Organelles Vacuoles – are an organelle used to store water in plants, and wastes in animal cells. The vacuoles in plant cells are large, while in animal cells they are very small.

Types of Organelles Lysosomes – are vesicles that contain digestive enzymes that break down food particles, cell wastes and worn-out cell parts.

Plant vs. Animal Cells There are several differences between plant and animal cells. Only plants cells have: Cell Wall – this is a tough rigid structure that surrounds the cell membrane, and it gives plant cells their box shape. The cell wall protects the cell by supporting the growing cell. Chloroplasts – trap energy from the sun and change it to chemical energy. Photosynthesis – Light + CO2 + H2O  food (glucose) + O2