Parts of the Cell or the Organelles of a Cell

• Cytoplasm

  • Jelly-like material inside the cell
  • Entirety of the cell contained by the cell membrane
• Cytosol


  • The fluid inside the cell where the organelles and other cell components are suspended (ex. enzymes, metabolic intermediates, and inorganic salts)
  • Part of the cytoplasm not taken up by organelles
• Cytoskeleton


  • A collection of fibers that can provide support for the cell and its organelles
  • Play a major role in cell movement
  • Presence of centrioles for animal cells (microtubules organizing centers; structures from which microtubules emerge; only found in some lower plant forms for plant cells)
  • Plant cells have many small nucleation sites here
• Ribosomes


  • Not membrane-bound organelles
  • Make protein (protein synthesis) which is important because that's what so much of genetic material that, DNA, codes for, protein
  • Can be free in the cytoplasm but can also be attached to another organelle
• Nucleus

  • Holds the genetic material (ex. DNA)
  • Controls the cell's activities
  • Inside it is the nucleolus (composed of RNA and proteins, which form around specific chromosomal regions; where ribosomes can be produced)
• Endoplasmic reticulum (ER)

  • Has detoxifying enzymes
  • Processes molecules for the cell, like protein folding, and it's highly involved in transporting those molecules around
  • Produces and stores protein
• Golgi apparatus

  • The ultimate packaging center
  • Has enzymes for the modification of molecules (proteins) it may receive and sorts it
  • Can determine where to send those molcules, including some that may eventually be sent to the membrane so they can be secreted (sent out of the cell)
  • Involved in the synthesis and secretion of glycoproteins
  • Can receive items from the transport vesicles pinched off of the ER
• Mitochondria (mitochondrion)


  • Powerhouse of the cell
  • Makes ATP (used to perform functions necessary for life) energy in a process called cellular respiration
  • Runs on glucose (sugar) and needs the presence of oxygen to efficiently make ATP energy
• Plastids


  • Found only in plants
  • Storage of metabolically important substances such as starch (amyloplasts), oil (elaioplasts), proteins (proteinoplast), and colored pigments (chromoplasts)
• Chloroplasts


  • Type of plastid which contains green pigment (chlorophyll) that captures light energy
  • Make glucose by using light energy in a process known as photosynthesis
• Vacuole

  • Acts as storage for materials
  • Fill up space
  • Plant cells can have one large central vacuole while animal cells can have smaller and several vacuoles
  • Can also have digestive functions
  • Provide space to degrade waste substances
  • Takes up 90% of the space in plant cells
• Cell wall

  • Present in plants only and some prokaryotes
  • Around the plasma membrane
  • Rigid and composed of cellulose
  • Gives the plant cell a fixed angular shape
  • Its absence on animal cells causes it to be round and irregular in shape
  • Offers additional protection and shape maintenance
  • Provides rigidity and support against mechanical rupture of the cell
• Lysosome

  • Functions for intracellular digestion and possesses hydrolytic digestive enzymes (breaks down biomolecules)
  • Acts against foreign materials by engulfing and degrading them
  • Involved in cell processes like secretion, plasma membrane repair, cell signaling, and energy metabolism
  • Found in animal cells but are still debated over its presence in plant cells
• Peroxisome

  • Destroy peroxides which cause oxidation in the cell
  • Possesses oxidative enzymes
  • Metabolize waste
• Flagella

  • In plants, only reproductive cells (gametes) can have this (ex. sperm of bryophyte)
  • Also found only on reproductive cells of some animal cells (ex. human sperm)
• Cilia


  • Found in most animal cells
  • Examples: cilia in our respiratory systems that help move debris and mucus, cilia in the female reproductive system to help sperm move towards the egg
• Plasmodesmata


  • Found in plant cells
  • Connects two plant cells
• Gap junction


  • An analogous structure in animal cells that connects the cytoplasm of two adjacent cells
• Rough Endoplasmic Reticulum

  • has ribosomes attached to it
  •  involved in the synthesis, modification, and transport of secretory proteins
  • molecules from this can be sent away in vesicles (small sacs) that pinch off the ER themselves
• Smooth Endoplasmic Reticulum

  • has no ribosomes
  • is involved in the synthesis of lipids and hormones
  • also involved in detoxification (one reason why liver cells have a lot of smooth ER)
• What animal and plant cells have and don't have

  A) yes

  B) yes

  C) yes

  D) yes

  E) no

  F) bigger

  G) many

  H) debated

  I) no

  J) yes

  
• Cell membrane or plasma membrane

  • Semi-permeable
  • Only lets certain select materials in and out which allows the cell to control its own biochemistry
  • Keeps things in the cell stable (homeostasis)
  • Made of a phospholipid bilayer (two layers of lipids)
  • Its head is polar (have unequal sharing of electrons among atoms) while its tail is nonpolar (have equal sharing of electrons among atoms)