Cell structure Lecture 2

Cell Membrane – all cells FUNCTION- The cell membrane regulates what enters and leaves the cell and also provides protection and support Takes in water and food and eliminates waste STRUCTURE - The membrane is a double-layered sheet called a lipid bi-layer Polar heads face outwards and non-polar tails face inwards Embedded in the membrane are protein channels/pumps and carbohydrates

B. Cell Wall – plants and bacteria Where is it found? Found in almost all prokaryotes Found in plants, fungi, and algae NOT found in animals Lies outside of the cell membrane Allow for movement of certain molecules Water, carbon dioxide, oxygen and some other substances The main function of the cell wall is to provide support and protection to the cell Structure - Cell walls are made of carbohydrates i.e. cellulose fiber

Nucleus - eukaryotes Function - The nucleus controls most cell processes and contains the hereditary information of DNA Structure - Consists of 4 parts Nucleolus – small densely packed region where ribosomes are created Nuclear Envelope – double membrane layer surrounding the nucleus Nuclear Pores – a perforations within the nuclear membrane Chromatin – this is the granular material within the nucleus Chromosomes – the condensed form of chromatin just before a cell divides

Cytoskeleton – all cells Function - A network of protein filaments that helps the cell keep its shape, also used in many forms of cell movement (in the documentary the virus traveled along these filaments) Structure - Made up of microtubules and microfilaments

Ribosomes - eukaryotes Function -Ribosomes assemble proteins following the coded instructions that come from the nucleus Structure - Ribosomes are made of protein and RNA

Endoplasmic Reticulum - eukaryotes Function - The organelle in which components of the cell membrane are assembled and some proteins are modified Structure Types Smooth ER – contains collections of enzymes that perform specialized tasks, such as the synthesis of lipids (fats) Rough ER – the part that is involved in the synthesis of proteins; has ribosomes embedded in the membrane

Golgi Apparatus - eukaryotes Function -Proteins made by the ER move to the Golgi apparatus where enzymes attach carbohydrates and lipids Structure – folded sacs involved with modifying and packaging proteins

Lysosomes – animal cells Structure - Are small organelles filled with enzymes Main function is to break down lipids, carbohydrates and proteins into particles that can be used by the cells Also helps to break down old organelles, remove debris from the cell

Vacuoles – all cells Function - Storage for the cell Stores materials such as water, salts, proteins and carbohydrates Plants have a single large vacuole (mostly water)

Chloroplasts – plant cell Found in photosynthetic organisms Function - Use energy from sunlight to make energy-rich food molecules in a process known as photosynthesis Structure – Light capturing pigment Contains thylakoids and chlorophyll Contains its own DNA

Mitochondria – eukaryotes Function - Releases energy from stored food molecules in a process called cellular respiration Found in eukaryotes Structure – Small organelle that contains its own DNA (you get it from your momma)

Organelle DNA Lynn Margulis suggested that mitochondria and chloroplasts were originally prokaryotic organisms that were enveloped by a eukaryotic cell The DNA in mitochondria comes almost exclusively from the mother

Movement through the membrane Facilitated diffusion – no energy required Molecules such as glucose sugar that cannot cross the cell membrane’s lipid bilayer directly can move through protein channels from an area of high concentration to an area of low concentration with the concentration gradient Active transport – energy required When a molecule has to move against the concentration gradient Each pump is used to move a specific molecule across the membrane Example: sodium potassium pump moves sodium out and potassium in (

The removal of large amounts of material from a cell Endocytosis The process of taking materials into the cell by means of infolding or pockets of the cell membrane Exocytosis The removal of large amounts of material from a cell exocytosis

ANIMAL AND PLANT