Chapter 3 - Cells Flashcards
3 major parts of a cell
- Nucleus
- Cytoplasm
Cell membrane
- Cytoplasm
Signal Transduction
series of biochemical reactions which allow cells to receive and respond to messages reaching the cell membrane
Membrane Proteins structure
- can either be globular, fibrous or rodlike in shape
- Integral meaning extending into the bilipid layer and peripheral meaning it may protrude from one or both sides
Types of Membrane Proteins
- Receptors: responds to extracellular signals
- Pores/channels/carriers: admit water/transport ions or small molecules/transport large molecules
- Enzymes
- Cell surface proteins: establish self
- Cellular adhesion molecules: enable cells to stick to each other
Cel Adhesion Molecules
proteins which guide the movement of cells
Example of CAM
a white blood cell in the blood stream needs to slow down when it reaches the cut site which happens due to a CAM protein called selectin which coats the white blood cell and provides traction. Another CAM called integrin contacts an adhesion receptor protein in the capillaries near the cut site which protrudes through the capillary space and picks up the slow passing white blood cell
○ Selectin coats WBC and anchor them to capillary walls ○ Adhesion Receptor proteins bind to integrins to help WBC leave the capillary
Integrins(CAM Process)
Integrins: on the surface of WBC which directs them through capillary walls and towards infection site
Effects of Faulty Ion Channels
- Mutations in sodium channels can cause an inability to feel pain
- Mutations in potassium channels can disrupt electrical activity of the heart and impair hearing
- Abnormal Chloride channels are the cause of cystic fibrosis due to clogged pancreas and salty sweat as a result of thick mucus which causes difficulty breathing
- Mutations in potassium channels can disrupt electrical activity of the heart and impair hearing
Endoplasmic Reticulum
a tubular transport system composed of membranous flattened sacs which goes from nucleus towards the cell membrane
○ Works in synthesizing proteins or lipids and either secretes them out of the cell or uses them as the cell membrane grows/repairs
Types of ER
○ Rough: folds proteins into their 3d shapes and ships them to the Golgi
○ Smooth: synthesizes lipids, absorbs fat from the digestive tracts and breaks down certain drugs
- Abundant in liver and skeletal cells
Cytoplasmic Organelles
- ER
- Ribosomes
- Vesicles
- GOlgi
- Mitochondria
- Lysosomes
- ## Peroxisomes
Structure of Mitochondria
- Cristae: Inner folds
- Inner membrane
- Outer membrane
Lysosomes:
contain hydrolytic enzymes which digest proteins, carbs, nucleic acids and bacteria, debris or old cell parts
- Produced in the ER and packaged in the Golgi
Peroxisomes
abundant in liver and kidney cells and contain enzymes called peroxidases which release hydrogen peroxide(H202) to break down cells and catalase to decompose hydrogen peroxide
Function of Enzymes in outside layer of Peroxisomes
○ Synthesis of bile acid used in fat digestion
○ Breakdown of lipids
○ Degradation of rare biochemicals
- Detoxification of alcohol
Cytoplasmic Structures
- Cytoskeleton
- microfilaments
- microtubules
- intermidiate filaments
- centrosomes
- cilia
- flagellum
Microfilaments
tiny rods of actin which form meshwork’s or bundles and provide cellular motility
- E.g. make up myofibrils which shorten or contract muscle cells
- E.g. microfilaments in cell membrane aid in cell motility
Microtubules
long slender tubes of tubulin 2-3x wider than microfilaments which are rigid due to having globular proteins attached in a spiral pattern
- Enables it to maintain cell shapes
- Provide conduits/channel for conveying organelles
Intermediate Filaments
take the general form of dimers(protein pairs) entwined into nested coiled rods which are suited to resist tension
- E.g. intermediate filaments made of keratins are abundant in actively dividing epidermis cells which form a strong inner scaffolding to help cells attach and form a tough protective barrier
Centrosome
a non-membranous structure consisting of two centrioles which are built of microtubules organized as 9 groups of 3
- Migrate to either side of the nucleus in cell division to produce spindle fibers
Cilia
hairlike extensions of the exposed surfaces of cells which move things along the cell surface
- Made of microtubules
- Moves things past the cell e.g. mucus down the respiratory tract
Flagellum
Relatively long, motile process that extends from the surface of a cell and causes it to move
Components of Cell nucleus
- Nucleus is enclosed in a double layered nuclear envelope
○ Inner and outer membranes are joined at places called nuclear pores
§ Pores let our mRNA but not DNA- Nucleolus: a small dense body composed of RNA and protein which has no surrounding membrane and is the site of ribosome production
Chromatin: condensed DNA around histones