Chapter 3/4: Cells & Membranes Flashcards by Phuoc Tran

Cell

The smallest unit of life

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Cell: self-contained structure capable of:

1) Replication
2) Maintenance

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Cell theory

1) Everything living thing is composed of one or more cells
2) Cells come from pre-existing cells

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Cells are Small (Usually)

1) Unknown until microscopes were available (mid-1600s)
2) Some cells are quite large though

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Surface are-to-volume ratio definition

1) As an object gets larger, its surface area increases more slowly than its volume
2) Cells must be able to interact with the environment (exchange materials)

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Two types of cells

1) Prokaryotes
2) Eukaryotes

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Prokaryotes

Small and relatively simple (domain Bacteria and Archaea), single-celled organisms

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Eukaryotes

Typically larger and have organelles (domain Eukarya; plant and animal cells), single or multicellular organism

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Plasma membrane

Phospholipid bilayer separating extracellular (outside) from intracellular (inside)
1. Necessary for homeostasis
2. Selectively permeable
3. Used in communication, and interaction with other cells

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DNA

Found in nucleoid

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Cytosol

Liquid inside the plasma membrane

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Ribosome

RNA/protein structures used for protein synthesis

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Prokaryotes (Optional structures)

1) Cell wall: (structure/protection)
2) Capsule: (defense) prevent dehydration, recognition
3) Flagella (movement)
4) Pili (attachment/transfer of materials)
5) Cytoskeleton (structure)

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Eukaryotes

Compartmentalize by developing distinctive parts, eukaryotic cells isolate functions into distinct organelles

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Origins of Eukaryotes

1) Endosymbiosis
2) Invagination

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Endosymbiosis

Absorption of one prokaryote by another forms a symbiotic relationship

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Photosynthesis makes

More energy available and similar size, independent DNA, and fission

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Invagination

Plasma membrane folded in on itself making a pocket’s that become specialized

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The nucleus contains genetic materials (DNA)

Chromosome that contain genes (Instruction)

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Nucleolus

Responsible for producing rRNA

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Nuclear envelope

Double membrane that covers the nucleus and controls access

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Ribosome

Sites of protein construction

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Free ribosome float in

The cytosol

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Bound ribosomes are attached to

The endoplasmic reticulum and making it rough or bumpy

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Mitochondria and chloroplasts

Have their own ribosomes

Rough Endoplasmic Reticulum (RER)

Bound ribosomes and production with modification of proteins

Smooth Endoplasmic Reticulum (SER)

No bound ribosomes

Metabolic processes

Synthesis of lipids, modification of drugs/poisons

Alcoholics/drug addicts have more

Smooth ER than non-users

Large in cells that produce, what?

Hormones

Golgi apparatus (body):

Transport hub (warehouse and shipping center of the cell

Golgi apparatus receives

Transport vesicles (bubbles of membrane holding some material)

Golgi apparatus modifies and produces some, what?

Molecules

Golgi apparatus produces, what?

Transport vesicles

Lysosomes

Bag of digestive enzymes

Lysosomes used to

Digest/recycle macromolecules, phagocytosis like cellular eating

Autophagy

Recycling of cellular material

Vacuoles

Compartments filled with aqueous solutions (large vesicles)

Eukaryotic storage

Waste, toxins, or distasteful substances

Eukaryotic structure

Central vacuoles (plants)

Eukaryotic digestion

Food Vacuoles

Eukaryotic regulation

Contractile vacuoles

Maintain water balance

Mitochondria

Energy conversion (from chemical bonds into ATP) via cellular respiration

Mitochondria have double-layered of what?

Organelle

Mitochondria density and size vary with

Cell type

Plastids

Specialized group of plant organelles

Chloroplast

For photosynthesis, green color from chlorophyll and similar to mitochondria with double membrane design

Cytoskeleton

A fiber network extending across the cytoplasm key to cell organization, movement

Composed of 3 fiber types

1) Microtubules 2) Microfilarments 3) Intermediate filaments

Cilia

Short, numerous structures hair like

In multicellular organisms can help move, what?

Extracellular material

Flagella

Longer structure, often single or in pairs used to propel the organism

Extracellular structure

1) Outside the plasma membrane: Extracellular 2) Inside the plasma membrane: Intracellular

Plant cell walls

1) Provide a rigid frame of support, shape 2) Protect contents of cell

Animal cells do not have walls

1) Extracellular matrix containing collagen (proteins) & proteoglycans (sugars) 2) Provide adhesion, protection, communication, movement, & certain physical properties

Plasma membrane

Separates the intracellular from the extracellular

Selective permeability

Allows some substances to cross but not others (regardless of size) 1) This allows the inside of the cell to be different from the outside 2) Necessary to get nutrient in and waste out

Phospholipids have both

Hydrophilic and hydrophobic regions and form a bilayer sandwich

Fluid mosaic model

Not a solid, inflexible barrier

Cholesterol helps

Stabilize and maintain membrane flexibility at normal temperatures and surface proteins move freely

Receptors

Receive extracellular information

Recognition

Identification (typically of non-self cells)

Carbohydrate chains also are used for

Cell recognition

Transport

Allow large molecules to enter/exit the cell

Enzymes

Enhance reactions on the inner or outer membrane surface

Passive transport

Requires no energy; dependent on molecular motion

Active transport

Requires energy; independent of molecular motion

Diffusion

The movement of molecules from areas of higher concentration to areas of lower concentration (moving down a concentration gradient)

Solute

The molecule (particle) of interest must be dissolved in a liquid or gas

Solvent

The liquid or gas that the solute is dissolved in

Types of diffusion

1) Simple 2) Facilitated

Simple diffusion

Unassisted movement (either no barrier or crossing membrane alone)

Facilitated diffusion

Assisted (non-energy requiring) movement across a membrane (generally using a transport protein)

Osmosis

A specific type of diffusion only referring to the movement of water across a semi-permeable membrane

Tonicity

The concentration of extracellular to intracellular solutions

Hypertonic

Higher solute concentration

Hypotonic

Lower solute concentration

Isotonic

Inside and outside are equal

Primary active transport

Use ATP directly to move molecules across a membrane

Secondary active transport

Use indirect energy to move molecules across a membrane

Molecules too large to move through the membrane enter/exit via, what?

Endocytosis or exocytosis

Bubbles of membrane containing

Material too large or otherwise incapable of physically crossing the membrane

Chapter 3/4: Cells & Membranes Flashcards

(83 cards)