Ch 8 Cell Structure

Syllabus Describe the function of & identify the: mitochondria, chloroplast, nucleus, nuclear pores, ribosomes & DNA.

The Cell The cell is the basic unit in living things.

Plant Cell as seen under a light microscope

Cells All living things are composed of one or more cells. Cells are the basic units of structure and function in living organisms. Cells come only from reproduction of existing cells.

Cytoplasm Cytoplasm is a clear jelly like fluid that fills the cell It is the medium for all the chemical reactions It contains all the organelles suspended within the cell.

Organelles An organelle is a structure found in a cell that carries out a specific function.

Organelles we need to know Cell membrane Nucleus Mitochondria Chloroplast Ribosomes DNA Cell Wall Vacuole

Learning Check What are Cells? What are organelles? Can you name 8 organelles?

Animal Cells contain the following structures: Cell Membranes Mitochondria Nucleus Cytoplasm Only the cell membrane, the cytoplasm and the nucleus can be seen under the light microscope.

Ultra Structure of an animal cell

Cell / Plasma Membrane are made up of phospholipids and proteins. are semi permeable / selectively permeable - controls the entry and exit of molecules to the cell. surrounds the cell function is to control the entry and exit of molecules to the cell

Learning Check All cells have a cell membrane. What are they composed of? What are its functions?

Plant Cells Plant cells also contain other organelles: Cell walls Chloroplasts Large Vacuoles

Ultra structure of an plant cell

Cell wall The cell wall is composed of cellulose fiber, polysaccharides and proteins rigid, this gives plant cells a very defined shape gives support, strengthens and prevents the cell from bursting.

Vacuoles Vacuoles are membrane-bound sacs found within the cytoplasm of a cell They provide 1. structural support 2. Storage of water, food and chemicals, Plant cells have larger vacuoles

Mitochondria function is to provide energy (respiration) Cells e.g. muscles with lots of mitochondria produce a lot of energy

Ribosomes Contain RNA & protein Their function is to make proteins

Chloroplasts only in plants are green and carry out photosynthesis

Learning check What organelle carries out photosynthesis? What type of cells have large vacuoles and cell walls? What is the function of vacuoles? What is the function of cell walls? What makes cells walls rigid?

Nucleus function is to control the cell contains chromosomes which are made of DNA elongated, non-dividing chromosomes are called chromatin

DNA deoxyribonucleic acid found in chromosomes or chromatin in the nucleus

Nucleolus located in nucleus makes ribosomes

Prokaryotic cells do not have a nucleus or membrane-enclosed organelles are small and more primitive are found as bacteria

Eukaryotic cells have a membrane-enclosed nucleus and cell organelles are larger and more advanced are found as plant and animal cells, fungi and amoeba