Science 8 - Cell structure and transport

Flagella

A long, whip-like tail used to help 'swim;' made of nine microtubule pairs surrounding two microtubules

Cilia

The 'hairs' on the outside of some cells that help with movement; made of nine microtubule pairs surrounding two microtubules

Plasma membrane

A selectively-permeable phospholipid bilayer separating the inside and outside of the cell

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Nucleus

An organelle containing DNA which controls the cell's activities; only found in eukaryotes

Nucleolus

Found inside the nucleus; produces ribosomes

Nuclear pores

Holes in the nuclear envelope (nucleus' membrane) that allow materials to pass in and out of the nucleus

Cytoskeleton

A network of protein filaments that help keep the cell's shape and help keep things 'suspended' in the cell

Peroxisome

An organelle that breaks down large molecules (especially fatty acids)

Mitochondrion

Double-membrane organelle that makes ATP through the process of cellular respiration; has its own DNA and can reproduce independently of the cell

Cellular Respiration formula

C6H12O2 + 6O2 ------> 6CO2 + 6H20 + 'Energy' (ATP)

Cristae

Folds in the inner membrane of mitochondria

Matrix

The cytoplasm inside mitochondria

Where does cellular respiration take place in the mitochondria?

The inner membrane

Vacuole

An organelle that acts as a storage area

Lysosome

The 'trash can' of the cell; an organelle containing enzymes which break down substances

Rough Endoplasmic Reticulum (RER)

A folded organelle with attached ribosomes that packages and transports proteins around the cell

How does the RER work?

Ribosomes are partly submerged in the membrane of the RER, which means that the ribosomes can drop their synthesized proteins into the lumen (tube shaped inner part) of the RER, which can then carry the proteins around the cell

Smooth Endoplasmic Reticulum (SER)

The part of the ER with no ribosomes on its surface; packages and transports proteins

Centriole

Organelle that helps cell division; in animal cells only

Golgi Apparatus

Organelle that modifies, sorts, and packages proteins from the endoplasmic reticulum; often, these proteins are released in exocytotic vesicles, which then fuse their membrane with that of the cell and empty their contents into the outside.

Cell Wall

A rigid structure that surrounds the cell membrane and provides support to the cell; only in plant cells

Chloroplast

Double-membrane organelle mostly found in plant cells that is the site of photosynthesis; has its own DNA and can reproduce independently of the cell

Photosynthesis formula

6CO2 + 6H2O + sunlight ---> C6H12O6 + 6O2

Thylakoid

Found within chloroplasts; contains the components for photosynthesis

Grana (sing. granum)

Stack of thylakoids in a chloroplast

Stroma

Cytoplasm within chloroplast

Water Vacuole / Central Vacuole

A large vacuole found in plant cells which can fill with water. When they are completely full, they exert turgor pressure on the cell wall, which makes the cell rigid and supports the structure; this is why plants wilt when they don't have sufficient water.

Biogenesis

The idea that all life comes from preexisting life

Abiogenesis

The idea that life can spontaneously generate (incorrect)

Louis Pasteur

Invented pasteurization and disproved abiogenesis with the experiment in the picture

Anton von Leeuwenhoek

Invented the microscope

Robert Hooke

Discovered cells and coined the term 'cell' by looking at cork cells

Robert Brown

Discovered and named the nucleus

Theodor Schwann

Concluded that all animals are made of cells

Cell Theory

1) Cells are the basic unit of structure and function in living organisms. 2) All cells come from preexisting cells (latter discovered by Rudolf Virchow)

Prokaryote vs Eukaryote

Prokaryote: lack membrane-bound organelles; simple and small. Eukaryotic: possess membrane-bound organelles; have nuclei, mitochondria, etc; more complex, larger

Different shapes of bacteria

Rod-shaped: Bacilli.
Spiral-shaped: Spirilla.
Spherical: Coccus.

Nucleoid

A dense region of DNA in a prokaryotic cell; NOT the same as the nucleus

Symbiotic relationship

The relationship between two species that live in close association with each other

Mutualistic symbiotic relationship

Organisms both benefit; ex. gut bacteria in humans' stomachs

Commensalistic symbotic relationship

One organism benefits, one is unaffected; ex. ramoras and sharks

Parasitic symbiotic relationship

Benefits one organism, harms the other; ex. tapeworm in a human intestinal tract

Endosymbiotic Theory

Theory that simple prokaryotic organisms began living in symbiotic relationships that eventually became obligatory as one cell engulfed the other (proposed by Lynn Margulis)

5 kingdom system

Bacteria Protists Plants Animals Fungi

Passive transport

No Energy Required – Moves with the Concentration Gradient

Diffusion

Movement of molecules from high to low concentrations

Facilitated diffusion

Movement of molecules from high to low concentration with the help of a transport protein (channel or carrier proteins)

Osmosis

Diffusion of water through a semipermeable membrane from an area of high water concentration to low water concentration.

Active transport

Requires energy - Moves against the concentration gradient

Sodium-Potassium Pump

Moves 3 Na+ out of the cell and 2 K+ into the cell using ATP. It maintains electrical charge balance, crucial for nerve impulses and muscle contractions.

Endocytosis

The process where the cell engulfs large molecules by forming a vesicle

Phagocytosis

Engulfing solid particles like bacteria

Pinocytosis

Engulfing liquids

Exocytosis

The process where the cell expels materials by fusing a vesicle with the membrane

Isotonic solution

No net movement. The cell stays the same whether it is an animal or plant cell.

Hypotonic

Water enters the cell. An animal cell may swell and burst. But a plant cell would have turgor pressure and wouldn’t burst because it has a cell wall.

Hypertonic

Water leaves the cell. The animal cell would shrink, and the plan cell would go through plasmolysis when the cell membrane pulls away from the wall.

Channel proteins

Allow specific molecules to pass and is used in facilitated diffusion. They do not require energy.

Carrier proteins

Binds to substances and change shape to transport them. It is used in active transport. They require ATP.

Glycocalyx (Carb chains)

Helps with cell recognition and signaling

Cholesterol

Maintains membrane fluidity and stability, preventing it from becoming too rigid or too fluid

Equilibrium

Occurs when molecules are evenly distributes across a membrane

Equilibrium in osmosis

Water keeps moving, but the concentrations on both side of the membrane remain equal.

How does the Sodium Potassium pump work

 

1. 3 Na⁺ ions inside the cell bind to the pump (it has a high affinity for Na⁺ at this point).

1. The pump uses 1 ATP. ATP gives energy by losing a phosphate (becoming ADP).

2. The pump changes shape and releases the 3 Na⁺ ions outside the cell.

3. Now, the pump has a high affinity for K⁺. 2 K⁺ ions outside the cell bind to it.

4. The pump returns to its original shape and releases the 2 K⁺ ions inside the cell.

Pseudopods

Extensions of the cytoplasm and certain cells (amoebas or white blood cells) use them to move or engulf things.

Bulk transport

Moving big things or lots of things at once. It needs ATP because it involves rearranging the membrane.