Cytology Cell Organelles Advanced Biology Organelles n Components

Cytology: Cell Organelles Advanced Biology

Organelles n Components of eukaryotic cells only n n Prokaryotic cells only have a cell membrane, cytoplasm/cytosol, DNA, and ribosomes Called “internal compartments” n Allow the cell to carry out specific functions

Endosymbiotic Theory n n Theory that the mitochondria and the chloroplast were originally prokaryotic cells Eukaryotic cell took in these structures to help them with everyday functions n n n Animal and plant cells took in the mitochondria Plant cells took in the chloroplast Explains why mitochondria and chloroplasts have double membrane, ribosomes, and their own set of DNA

Cell Membrane Consists of lipids (phospholipids) and proteins n Regulates what goes in and out of the cell n Known as the Fluid Mosaic Model n n n Moves constantly; allows for flexibility Phospholipids and proteins like a mosaic look

Cytoskeleton n Microfilaments (3 -6 nm) n n Muscle contraction Cell movement/contractions Cytokinesis (actual separation of cells during cell division Microtubules (20 -25 nm) n n Aid with cell shape Provides a “track” for organelles to move on within the cell Make up the spindle fibers which guide chromosomes during cell division Found inside cilia and flagella (help with locomotion)

Cytoplasm and Cytosol Cytoplasm: space inside of the cell that is not an organelle n Cytosol: fluid like substance that fills the cytoplasm n

Nucleus n n n Center sphere in cell; holds the DNA Has its own double membrane (made of phospholipids) Parts n n Nucleolus: ribosome assembly r. RNA DNA: holds genetic information (circular in prokaryotes and helix in eukaryotes) Nuclear envelope: membrane that surrounds the nucleus Nuclear pores: openings in the nuclear membrane; controls what goes in and out of the nucleus

Endoplasmic Reticulum Series of membrane tubes and channels that is connected to the nucleus n Sacs are called cisternae and the space within the cisternae is called the lumen n When there is enough product (proteins/lipids/steroids), they are pinched off as vesicles, which will move to the Golgi to be packaged for export n

Types of Endoplasmic Reticulum n Rough Endoplasmic Reticulum (RER) n Directly attached to the nucleus (allows for movement of molecules between the two n n m. RNA can move directly to the ribosomes on the ER to make proteins Has ribosomes on it; makes it appear “rough” Makes proteins Smooth Endoplasmic Reticulum (SER) n n n No ribosomes Makes lipids (steroids hormones) and oils Detoxification of harmful chemicals

Ribosomes Site of protein synthesis n Can be free inside the cell or attached to the RER n Made of ribosomal RNA (r. RNA) n

Golgi Apparatus n Set of membranous sacs n n Located near the endoplasmic reticulum “Post office” of the cell n n Sorts and packages proteins and lipids according to destination Uses vesicles for transportation; pinched off portion of the G. A.

Mitochondria Has own set of DNA and ribosomes n Is the “powerhouse” of the cell n n n Site of cellular respiration n n Extracts energy from food molecules Stores energy in bonds of ATP Muscle cells have many of these

Lysosome n Membranous sac of digestive enzymes n n “Trash dumpster” of the cell n n n Made by Golgi Apparatus Contains digestive enzymes Gets rid of large molecules, wastes, and malfunctioning organelles Tay-Sachs occurs due to the fact that the lysosome isn’t digesting lipids, so fatty substance accumulates on nerve cells

Plant Cell Organelles n Cell wall n n n Central vacuole n n Outer most covering; made of cellulose and chitin Some bacteria, protists, and fungi also have these Water filled pocket in cell Controls rigidity of the plant and stores nutrients and wastes Can make up to 90% of the cell’s volume Chloroplast n n Plastid that is the site of photosynthesis Contains chlorophyll (green pigment)

Extras n Capsule n n n Cilia n n Layer that is found outside of the cell wall on some bacteria Allows for adhesion to other surfaces (Streptococcus mutans-plaque) Fine, hair like projections that aid with locomotion Flagella n Long, whip-like projects that aid with locomotion

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