Accelerated Biology: Cells

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Nucleus

Stores most of the cell’s DNA and acts as a control center

Nuclear envelope

A double membrane around the nucleus that regulates traffic between the nucleus and cytoplasm

+Nuclear Pores: regulate what enters and exits the nucleus

Nucleolus

The center of the nucleus, which produces rRNA (ribosomal RNA), an important component of ribosomes

Cytoplasm

The fluid-filled region between the nucleus and plasma membrane

Mitochondria

Harvest energy from food molecules

Ribosomes

Build proteins/they can float freely or attach to rough ER

Endoplasmic reticulum (ER)

Helps manufacture a variety of cellular products

Rough: has ribosomes that produce protein

Smooth: has enzymes that produce lipids

Golgi apparatus

Receives, refines, sorts, and ships cell products

Vesicles

Membrane-enclosed sacs that store or transport materials

Cytoskeleton

A network of fibers that supports cell shape and helps movement

Lysosomes

Digestive-enzyme sacs that break down and recycle cell materials

Chloroplasts

Contains structures that convert light energy into food energy for plants during the process of photosynthesis

Central Vacuole

A storage sack that holds nutrients and water in a plant

Cell Wall

A rigid, protective layer on a plant cell made of cellulose that helps maintain cell shape

Flagellum

A whip-like structure that propels a cell

Animal cells

Have lysosomes and smaller vacuoles if present; have more flexible and round shapes

Plant cells

Have chloroplasts, a rigid cell wall, and a large central vacuole; has a box-like shape

Fluid

Molecules can move sideways past one another within the membrane

Mosaic

Many different proteins are scattered among the phospholipids

Cholesterol

Helps maintain membrane fluidity. In cold conditions, it prevents the membrane from becoming too rigid/in warm conditions, it helps keep the membrane from becoming too fluid

Integral proteins

Embedded in the phospholipid bilayer/can act as transport channels, anchors, or enzymes

Peripheral proteins

Loosely attached to the membrane surface/help maintain shape, attach to the cytoskeleton, support cell signaling, or speed chemical reactions

Lipid-anchored proteins

Covalently attached to membrane lipids and important in cell signaling

Glycocalyx

Sugar chains attached to proteins or lipids. These help with protein binding, cell communication, lubrication, and adhesion

Diffusion

Movement of particles from high to low concentration

Osmosis

Diffusion of water across a selectively permeable membrane

Facilitated diffusion

Movement from high to low concentration with help from a transport protein

Endocytosis

The cell brings materials into the cell

Exocytosis

The cell exports materials out of the cell

Hypotonic Solution

Lesser solute concentration outside of cell - water moves into the cell

Hypertonic

Greater solute concentration outside of cell - water moves out of the cell

Isotonic

Equal solute concentration inside and outside of cell - there is no net movement of water

Plasma Membrane

The outer boundary of the cell that regulates the movement of substances into and out of the cell is selectively permeable and a fluid mosaic (fluid: phospholipids and proteins can move sideways within the membrane; mosaic: it contains many different components arranged together)

Transcription

The nucleus transcribes DNA into mRNA

Translation

Polypeptides (proteins) are produced when the mRNA is translated out of the nucleus and into the rough ER, where the ribosomes read the mRNA and make protein out of it

Photosynthesis

Chloroplasts convert CO₂ + H₂O to Sugar + O₂

Cellular Respiration

Mitochondria convert Sugar + O₂ to CO₂ + H₂O + ATP

Cilia

Tiny hair-like structures that are attached to the surface of eukaryotic cells and detect chemical signals from the environment around the cell or whip back and forth to move fluids, mucus, or other cells across the cell’s surface

Protein Synthesis Pathway

1) DNA is transcribed into mRNA in the nucleolus.

2) mRNA leaves the nucleus and enters the cytoplasm.

3) A ribosome reads the mRNA and builds a polypeptide chain.

4) The polypeptide enters the rough ER to be folded and processed.

5) A transport vesicle carries the protein from the rough ER to the Golgi apparatus.

6) The Golgi modifies, sorts, and packages the protein.

7) A vesicle transports the finished protein to its destination or releases it through the plasma membrane.

Phospholipid Bilayer (plasma membrane)

The main structure of the membrane (hydrophilic heads face outwards to water outside of the membrane, and hydrophobic tails face inwards away from water)

Membrane Proteins (plasma membrane)

Transport substances, receive signals, or act as enzymes

Cholesterol (plasma membrane)

Helps maintain membrane fluidity and stability; enters through proteins

Glycocalyx/Carbohydrate chains (plasma membrane)

Help cells identify, communicate with, and attach to other cells

Passive Transport

Particles do not require energy to move from high concentration to low concentration (Diffusion, Facilitated Diffusion, Osmosis)

Active Transport

Particles require energy to move from low concentration to high concentration (Endocytosis and Exocytosis)