BJU Press Biology Chapter 5--Cytology

spontaneous generation

the idea that living things formed from non-living things

preformation

the idea that sperm and eggs contain miniature organisms that simply increase in size after conception

cytology

the study of cells

cell theory

1) cells make up all living things
2) cells only come from preexisting cells

unicellular organism

an organism that is made of only one cell

multicellular organism

an organism made of two or more cells that depend on each other to function

tissues

formed out of organized cells

organs

formed out of organized tissues that work together to perform a specific function

organ system

a group of organs that work together

organelles

the parts inside of a cell

eukaryotes

organisms containing membrane-bound organelles

prokaryotes

organisms that do not have membrane-bound organelles

cytoplasm

the jelly-like fluids that keep the organelles suspended

cytoskeleton

a system of fibers in the cytosol that maintain the cell’s shape and provides protein motors and a track to move substances around the cell using cytoplasmic streaming

cytosol

found in cytoplasm

capsule

only found in bacteria cells, protects the cell and prevents it from drying out, causing it to feel slimy

nucleoid

found only in prokaryotes, contains the genetic material for the cell and floats freely in the cytosol

flagellum (flagella)

an extension of the cytoskeleton, usually only one per cell but sometimes more, propels the cell through its environment using a protein motor

chloroplast

a type of pigmented plastid found in plant and algae cells, converts light energy into chemical energy

granum (grana)

found inside the chloroplasts, made of stacks of thylakoids that contain chlorophyll to carry out photosynthesis

ribosome

found in both prokaryotes and eukaryotes because it isn’t surrounded by membranes, contains proteins and lines up amino acids to make proteins, is either attached to the endoplasmic reticulum or floating freely in the cytosol

rough endoplasmic reticulum

transports compounds around the cell, studded with ribosomes, and helps maintain the cell’s shape

smooth endoplasmic reticulum

transports compounds around the cell and help maintain the cell’s shape, also processes fats and breaks down toxic substances in the liver

central vacuole

found mostly in plant cells; stores water, salts, sugars, and proteins; maintains turgor pressure to keep the cell wall rigid

turgor pressure

water pressure caused by the central vacuole that keeps the cell wall rigid

leucoplast

a type of colorless plastid found in plants and algae, stores starches, lipids, and proteins

cell wall

found in plants, fungi, algae, and bacteria; provides strength and rigidity to the cell, and contains pores so that materials can pass through it

nucleus

found in eukaryotic cells, the “control center” of the cell, contains genetic information

nucleolus

contains the RNA and proteins, the area of the nucleus where the ribosomes are assembled

chromatin

the genetic material of the nucleus; contains DNA, RNA, and ribosomes

lipid bilayer

has hydrophilic and hydrophobic ends, so it arranges into two layers: water loving on the outside and inside and water fearing facing each other

lysosome

a type of vacuole found in human, animal, and animal-like cells; contains digestive enzymes that digest food, kill bacteria and viruses, and recycle old cell parts

golgi apparatus

the “post office” of the cell, receives substances from the endoplasmic reticulum and packages them into vesicles to be sent to other places within the cell or outside the cell

centrosome

found in animal and human cells and builds parts for the cytoskeleton

mitochondrion

the “powerhouse” of the cell; transforms energy from sugars into usable energy, has an inner membrane with cristae (folds) that allow for more surface area to increase energy output and more proteins to be embedded in the membrane

cell membrane

surrounds the cell of prokaryotic and eukaryotic cells; protects the cell and allows certain materials to pass through it and contains proteins that perform several different functions for the cell

cilia

extensions of the cytoskeleton, often cover the entire or parts of the surface of a cell, propel the cell through its environment and move particles past the cell

homeostasis

the internal balance of a system that keeps conditions stable

dynamic equilibrium

the balance of changes and motions in a system

optimal range

the condition range where cells do not need to work as hard

range of tolerance

the range of conditions where cells can survive by working harder than normal

limit of tolerance

the range beyond the range of tolerance, ends up killing the cells

positive feedback

when a substance involved in a cellular process causes the process to speed up

negative feedback

when a cell involved in a cellular process causes the process to slow down or stop

concentration

the amount of solute dissolved in a solvent

osmosis

the diffusion of a solvent through a semipermeable membrane

semipermeable membrane

a membrane that allows some substances to pass through but not all

diffusion vs. osmosis

diffusion: goes high to low
osmosis: goes high to low in water

hypertonic solutions

produces movement of water out of cells that cause them to shrivel up

hypotonic solutions

produces water movement into cells that causes it to swell

isotonic solutions

equal amount of movement into and out of a cell that helps it maintain its shape

the four factors that determine whether a particle can pass through a cell membrane

particle size, particle shape, particle polarity, and membrane composition

facilitated diffusion

molecules move through the membrane with help from transport proteins

active transport

transport requiring energy

passive transport

doesn’t require energy