AP Bio Cell Types & Structures & Cell Size

Ribosome

makes proteins; can be on Rough ER (bound) which make proteins for membranes or for export out of cell; can be free in cytoplasm which make proteins for use in cell

Lysosome

cell organelle filled with hydrolytic enzymes needed to break down (digest) certain materials in the cell

Chloroplast

Site of photosynthesis, contains its own DNA & ribosomes.

Mitochondria

organelle that is the site of ATP (energy) production, oxidizes sugar to make ATP (cellular respiration); contains its own DNA & ribosomes

Endosymbiotic Theory

A theory that mitochondria and chloroplasts were once free living bacteria.

Cell membrane (plasma membrane)

encloses the cell, regulates the passage of materials into and out of the cell.

Cell wall

Surrounds cell membrane in some cells. Provides protection & support. Maintains cell shape. Prevents cell from taking in too much water. May contain cellulose, chitin, or peptidoglycan.

Nucleus

Control center of the cell. Contains DNA.

Nucleolus

Found inside the nucleus; produces ribosomes

Smooth Endoplasmic Reticulum

Makes lipids; metabolizes carbohydrates; detoxifies drugs & poisons; Stores calcium

Rough Endoplasmic Reticulum

Has ribosomes on surface that make proteins for export from cell; makes membranes

Golgi apparatus

stack of membranes in the cell that modifies, sorts, packages, and ships cell products

Centrosome

Involved in cell division in both plant & animal cells; microtubule organizing center (forms mitotic spindle)

Centrioles

Found in animal cells, stacks of microtubules that sit on top of centrosome, May play some role in cell division in animal cells.

Peroxisomes

Break down hydrogen peroxide to water, metabolize fatty acids, detoxify alcohol, convert fatty acids to sugar

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, provides support, and aids in movement. Fibers include microfilaments, microtubules, & intermediate filaments.

Cytoplasm

Fluid filled region between cell membrane & nucleus.

Plasmodesmata

channels through cell walls of plants that connect the cytoplasms of adjacent cells, allow water & solutes to move between cells

Nuclear membrane (envelope)

Surrounds the nucleolus and DNA. Controls what enters and leaves the nucleus.

Large central vacuole

the organelle that stores water in plants

Tonoplast

membrane surrounding the large central vacuole

Chromatin

DNA & protein in nucleus (DNA is not visible)

Chromosome

DNA & protein, visible during cell division (condensed)

Prokaryote

unicellular organism lacking a nucleus; bacteria

Eukaryote

A cell that contains a nucleus and membrane bound organelles

plant vs animal cells (structures present)

Plant - Chloroplast, cell wall, large central vacuole, plasmodesmata Animal - lysosomes, centrioles

Prokaryotes vs. Eukaryotes

- Prokaryotes have no nucleus or membrane bound organelles

- Eukaryotes have a nucleus and membrane bound organelles

- Both can reproduce and respond to the environment

Structures found in all cells

cell membrane, cytoplasm, DNA, ribosomes

Factors that limit cell size

Surface area and volume

Surface Area to Volume Ratio

Affects diffusion of nutrients and wastes into and out of cells.

Large Surface Area to Volume Ratio

Most efficient for diffusion

A cubed shape cell with a side length of 2 cm has a surface area to volume ratio of what?

3:1 (SA = 24 cm2 V= 8 cm3)

How do folded cell membranes benefit a cell?

Increase the surface area to allow more diffusion into or out of the cell.

Why is a smaller volume better for the cell?

The diffusion inside the cell is faster. There is less distance between cell membrane and organelles. Substances can get from the cell membrane to an organelle faster when the cell has a smaller volume.