Biology 8 - Unit 2 flashcards

The Cell Theory

The Cell Theory

• All living things are made up of cells

• Cells are the basic units of structure and function in living things.

• New cells are produced from existing cells.

Prokaryotes

• cells that do not enclose DNA in nuclei

• Smaller and simpler than eukaryotic cells. 

• They grow, reproduce, and respond to the environment, and some can even move by gliding along surfaces or swimming through liquids. 

• Bacteria are prokaryotes.

Eukaryotes

• cells that enclose their DNA in nuclei

• Larger and more complex than prokaryotic cells. 

• Contain dozens of structures and internal membranes. 

• Many eukaryotes are highly specialized. 

• Many types of eukaryotes: plants, animals, fungi, and protists

organelles

cellular structures act as if they are specialized organs.

Cell Wall

• Main function is to provide support and protection for the cell.

• Prokaryotes, plants, algae, and fungi have cell walls. 

• Animal cells do not have cell walls. 

• Cell walls lie outside the cell membrane and most are porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily.

Cell Membrane

• a thin, flexible barrier surrounding the cell

• controls what comes into and out of a cell

• Separates the cell from its surrounding environment.

• Helps cell maintain homeostasis

Cytoplasm

• the gel-like fluid portion of the cell outside the nucleus

• where many organelles are found.

Nucleus

• The Main Office - the control center of the cell.

• The nucleus contains nearly all the cell’s DNA and, with it, the coded instructions for making proteins and other important molecules.

Nuclear Envelope

• The nuclear envelope is dotted with thousands of nuclear pores

• allows material to move into and out of the nucleus. 

chromatin

a thread like complex of DNA bound to proteins spread throughout the nucleus.

Nucleolus

• small, dense region in the nucleus.

• where the assembly of ribosomes begins.

Mitochondria

• power plants of the cell.

• They convert the chemical energy stored in food into compounds that are more convenient for the cell to use.

Endoplasmic Reticulum

• Network of passageways that carries materials from one part of the cell to another. 

• Where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell.

Rough Endoplasmic Reticulum

• The portion of the ER involved in the synthesis of proteins 

• It is given this name because of the ribosomes found on its surface. 

• Newly made proteins leave these ribosomes and are inserted into the rough ER, where they may be chemically modified.

Smooth Endoplasmic Reticulum 

• The other portion of the ER is known as smooth endoplasmic reticulum (smooth ER) because ribosomes are NOT found on its surface. 

• The smooth ER contains collections of enzymes that perform specialized tasks, including the synthesis of membrane lipids and the detoxification of drugs. 

Ribosomes

• Small particles of RNA and protein found throughout the cytoplasm in all cells. 

• Assemble proteins by following coded instructions that come from DNA. 

Golgi Body

• Modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or release outside the cell.

• appears as a stack of flattened membranes.

Chloroplasts

• Plants and some other organisms contain chloroplasts. Not in animal cells!

• he biological equivalents of solar power plants.

• They capture the energy from sunlight and convert it into food/chemical energy during photosynthesis. 

• Contain the green pigment chlorophyll.

Vacuoles

large, saclike, membrane-enclosed structures that store materials such as water, salts, proteins, and carbohydrates. 

Vesicles

are used to store and move materials between cell organelles, as well as to and from the cell surface.

Lysosomes

• Remove “junk” that might otherwise accumulate and clutter up the cell.

• Breakdown lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell.

Cytoskeleton

helps the cell maintain its shape and is also involved in movement. 

Made up of Microfilaments and Microtubules

Centrioles

are located near the nucleus and help to organize cell division. Centrioles are not found in plant cells!

Organic Compounds

compounds that contain carbon

macromolecules

“giant molecules,” made from thousands or even hundreds of thousands of smaller molecules. 

Elements in Carbohydrates

carbon, hydrogen, and oxygen atoms (CHO)

Examples of carbohydrates

sugars, starches (potatoes), bread, rice…

Functions of carbohydrates

main source of energy for living things, and some organisms also use carbohydrates for structural purposes. (ex. Cell Wall = Cellulose)

Elements in lipids

carbon, hydrogen, and oxygen atoms (CHO)

Examples of Lipids

fats, oils, and waxes

Functions of lipids

long-term energy, stores more energy than carbohydrates, some are important parts of biological membranes and waterproof coverings, and some hormones are derived from lipids

Elements in proteins

carbon, hydrogen, oxygen, and nitrogen atoms (CHON)

Examples of proteins

The complement system, enzymes, and meat

enzymes

proteins that speed up chemical reactions

Functions of proteins

• controlling the rate of reactions and regulating cell processes (enzymes)

• forming cellular structures (cytoskeleton)

• transporting substances in or out of cells (protein channels)

• and helping to fight disease (antibodies and complement system)

• growth and repair of cells

Elements in nucleic acids

carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms (CHONP)

Examples of nucleic acids

DNA and RNA

Functions of nucleic acids

• Nucleic acids store and transmit genetic information.

• RNA helps to make proteins

Selectively Permeable

some substances can pass through while others cannot.

Diffusion

• Moving from area of HIGH conc. to area of LOW conc.

• Main method on how small molecules (O₂ and CO₂) move across the cell  membrane.

• Particles constantly move and collide randomly. Spread out evenly. (Random kinetic motion of particles)

• Requires no energy.

Equilibrium

• When the conc. of a system is the same throughout 

• (same conc. on both sides)

Osmosis

the diffusion of WATER through a selectively- permeable membrane.

Isotonic

• Concentration of water inside the cell is the same as outside

• no net movement of water

• cell stays the same

Hypertonic

• Low water concentration and high solute conc. outside the cell,

• water moves out of the cell

Hypotonic

• High water concentration and low solute conc. outside the cell

• water moves into the cell

Facilitated Diffusion

• Molecules that cannot directly diffuse across membrane get help from special proteins.

• called these protein channels

  • Allow specific things thru

  • NO energy needed!

Aquaporins

• Water channel proteins that allow water to pass right through them. 

• Without aquaporins, water would diffuse in and out of cells  very slowly. 

• Type of facilitated diffusion

Passive Transport

The movement of dissolved materials through a cell membrane without the use of energy

Active Transport

the movement of materials through a cell membrane using cellular energy (from low conc. to high conc.)

Transport Protein Pumps

• form of active transport

• When small ions and molecules are carried across membrane by protein pumps

  • Eg. Ca, K, Na

Endocytosis  

• The process of taking material INTO the cell

• a form of active transport.

Exocytosis

• The process of releasing large amounts of material OUT of the cell.

• a form of active transport.