04- Cell Structure Part II

04- Cell Structure Part II - Mitochondria − Structure:...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Mitochondria − Structure: − has 2 membranes, like nucleus − Outer membrane covers entire organelle − Inner membrane is extensively infolded, folded back and forth − inner membrane: folded into cristae − Compartment inside both membranes: matrix − part on the inside of the inner membrane − Has own circular DNA; can reproduce − mitochondria can divide and reproduce itself − Function: − Energy metabolism (cellular respiration) − manufacturing, digesting, processing of energy molecules − Structure/function relationship important for respiration − some cells have more mitochondria than others, muscle cells burn a lot of energy so they have a lot of mitochondria − Plants and animals both have mitochondria − Figure 4.17 − outer membrane − inner membrane is folded back and forth forming the crista − space between membrane—intermembrane space Plastids − Plastids: plant specific organelles − synthesizes/stores chemical compounds − often contains pigments (color) − pigments store light energy − stored and manufactured here − Only in plants − Types − Leucoplasts (colorless): store starch and fats, not pigments − Chromoplasts: contain nonchlorophyll pigment, can be any color and can change color depending on season/pigments being made − Chloroplasts: contain chlorophyll type pigments, contain pigments used for harvesting of light energy and production of energy molecules in plants Chloroplasts − Structure: − Outer membrane covers entire organelle − Inner membrane folded into stacked disks − thylakoid: single disk or single fold of inner membrane − grana: stacks of thylakoids − stroma: soluble material around grana − kinda like intermembrane space − Function − Site of photosynthesis in plant cells − convert light energy to chemical energy − structure/function similar to mitochondria − both harvest energy − double membrane is key to process energy molecules − No animals have chloroplasts, only in plants − Figure 4.18 − Grana is a stalk of thylakoids, space between granum is between stroma Vacuoles − Primarily found in plants (rarely in animals) − Prominent part in plant cells − Storage organelle − Store food, water, or waste − usually specific, don't store food & waste in the same vacuole..specific vacuoles have specific jobs − Central vacuole − Stores water: has water channels called aquaporins (specialized channel which help move water) in membrane − Involved in cell shape/water balance (osmosis) − vacuole gives cell its shape/structure − It pushes on the cell wall from the inside and gives it its shape − resist any pressure coming from the outside − pressure – turgor pressure − Involved in cell growth: grow by adding vacuolar volume, not cytoplasm − plant cells grow because central vacuole's size increases − animal cells­cytoplasm increases; plant cells­ vacuole increases Structural support for cells − Eukaryotic cells are relatively large: − cytoskeleton needed for internal support − More important in animals than plants for support − Plants use cell wall and turgor pressure (pressure from vacuole) − cell walls don't change their shape − Cytoskeleton is a dynamic structure − lengthen, shorten, rearrange, disassemble − animal cells can change their shape − Allows cell to move, change shape − gives structure and shape to cell − Multiple types of fibers involved − they are proteins − have specific jobs, specific locations, different properties within the cell Microtubules − Structure: − Largest cytoskeletal element (in terms of diameter) − they are tubes, cylinders − Hollow, unbranched tubes made of alpha­tubulin and beta­tubulin monomers − take individual proteins, put them together in a hollow tube, that makes a microtublue − Has different ends (+ and ­); dynamic − we can add and subtract monomers to one side and to the other, we cannot − add monomers to the front/positive end − can't add monomers to the negative end − cell can rapidly build up and break down microtubules as needed − Functions: − Forms spindle that separates chromosomes – spindle apparatus − involved in cell division by helping seperate chromosomes on spindle apparatus − Movement: cilia and flagella − outside the cell − propels cell − Transport within the cell − vesicles move along the microtubles, like a pathway − Structural support for cell Microfilaments − Structure: − Smallest cytoskeletal element (in terms of diameter) − Long unbranched fibers of actin monomers − actin: long, round, globular proteins linked end to end − Two strands of beads wound together (like a rope) − Also has different ends (+ and ­); dynamic − can break it, build it, rearrange it rapidly, … − build rapidly on positive end − break rapidly on negative end − Located near the inner surface of the cell membrane − Functions: − Signaling: scaffold for signaling molecules − since they're near the membrane, they can rapidly diffuse out − Movement: − all cell movement involves microfilaments − Give structural support to cell Intermediate filaments − Structure: − Intermediate in size (in terms of diameter) − Fibrous subunits (lamins) that are arranged into a solid cylinder − stable and durable filaments that form a branched network − don't break down or break up − once it's built up, it stays − Functions: − gives structure and stability − Gives shape to cell. − Form the nuclear lamina − Figure 4.20 − Model of cytoskeleton − micurotubles­ hollow, unbranched tube − intermediate filaments­solid rod, branched, form stable and rigid structure − actin filaments­ strands wound closely together, found close to inner layer of cell membrane Cell movement − Move using external structures: cilia and flagella (swimming movement) − made of microtubules − Move using microfilaments to change shape (amoeboid movement) − Like if you got in a giant balloon and someone in the balloon is walking − move cytoskeleton and push on one side of cell membrane, cell rolls forward − Both kinds of movement require motor proteins − convert chemical energy to mechanical − chemical energy: energy stored in chemical bonds (ex ­ ATP) − mechanical energy: energy of movement − convert checmical energy to movement − Dynein used in cilliar/flagellar movement − Dynein & kinesin also “walk” along the microtubules − Myosin associates with microfillaments − muscles are primarily made of myosin, which does the movement − actin provides the structure Extracellular matrix (ECM) − ECM includes two parts: − interstitial matrix—present in between cells − basement membrane—dense, sheet­like deposits on which epithelial cells are anchored − skin is partially made of epithelial cells which are anchored by basement − Consists of interwoven matrix of structural proteins and carbohydrate polymers − Secreted by surrounding cells − Cells in the matrix make the ECM − Cellular integrin proteins connect cytoskeleton to ECM − Type of ECM depends on surrounding cells − Dynamic structure—has many different functions, very complex − Anchored to one another and to the proteins on the outside. − Ex: bone tissue − ligaments, tendons − primarily made of carbs and proteins − few cells − Functions: − Provides structure, support, protection to cells; separates different tissues − keeps the same types of cells types together and separates them from different tissues and cell types − Intimately involved in regulating cell­cell communications − When a cell sends a signal, it has to go through the ECM. − Depot for growth factors (protein hormones) − growth factors are very complex − stimulated cell division in cell − do lots of things − Cells will make growth factors, then put them on the ECM. They go when the cell tells them to go because they're already ready to go. − Release of GFs by ECM causes local and rapid response by cells. − GF regulate many cellular processes − Instead of having the whole body respond, only a few cells in a certain location respond. − ECM key to growth, wound healing, angiogenesis (making new blood vessels), bone formation, tumors, … − ECM controls everything around it. Cell video: http://aimediaserver4.com/studiodaily/videoplayer/? src=ai4/harvard/harvard.swf&width=640&height=520 ...
View Full Document

This note was uploaded on 03/25/2010 for the course BIO 11000 taught by Professor Friedman during the Spring '10 term at Purdue University-West Lafayette.

Ask a homework question - tutors are online