Openstax Biology 2E Chapter 4

A Cell is

A Cell is

the smallest unit of a living thing.

What is the order of structure from cell to organism?

-Cells connect and form tissue

-Tissue connects to form organs

-Organs connect to form organ systems

-Organ systems connect to form organisms

Prokaryotic Cell Components

1. No nucleus or other membrane-bound organelle

2. Nucleoid region

3. Cell wall made of peptidoglycan used to maintain shape and prevent dehydration

4. Capsule made of polysaccharide

5. Flagella used for locomotion

6. Pili used to exchange genetic information during conjugation (genetic transfer through direct contact)

7. Fimbriae used to attach to host cell

8. Ribosome used for protein synthesis

9. Chromosomes (DNA)

10. Size .1-5.0 μm

Eukaryotic Cell Components

1. Size 10 - 100 μm

A microscope is

an instrument that magnifies an object

What is a micrograph?

An photo taken using a microscope

Magnification is

the process of enlarging an object in apperance

Resolving power is

the microscopes ability to distinguish two adjacent objects

Unified Cell Theory

1. One or more cells comprise all living things

2. the cell is the basic unit of life

3. New cells arise from existing cells

Organelle

“little organ”

Nuclear Envelope

membrane enclosing the nucleus. Protein lines pores allow material to move in and out. Ch

Chromatin

DNA plus associated proteinsNu

Nucleolus

condensed region where ribosomes are formed

Peroxisomes

metabolizes wastecyt

cytoskeleton microtubules

form the mitotic spindle and maintain cell shape

centrosome

microtubule organizing centerinter

intermediate filaments

fibrous proteins that hold organelles in place

microfilaments

fibrous proteins that form the cellular cortex

plasma membrane

Phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment

What is the role of the Lysosome?

• digests food and waste materials

• destroy pathogens using hydrolytic enzymes

What is a macrophage?

A group of white blood cells that are part of the body’s immune system.

cytoplasm

mitochondria

produce energy

vacuole

Rough Endoplasmic Reticulum (RER)

associated with ribosomes; makes secretory and membrane proteins

Smooth Endoplasmic Reticulum (SER)

Nucleus

Contains chromatin, a nuclear envelope, and a nucleus

Plasmodesmata (plants)

Channels that connect two plant cells

Central Vacuole (plants)

filled with cell sap that maintains pressure against cell wall

Cell Wall (plants)

• Rigid covering that protects the cell, provides structural support and maintains cell shape

• Primary component is cellulose.

Plastid (plants)

Stores pigments

Chloroplast (plants)

site of photosynthesis

Phospholipid

lipid molecule with two fatty acid chains and a phosphate-containing groupGl

Glycolipid

Lipid with carbohydrate attached

Glycoprotein

Protein with a carbohydrate attached

What does the plasma membrane control?

The passage of organic molecules, ions, water and oxygen in and out of the cell, as well as the exit of wastes such as carbon dioxide and ammonia.

Microvilli

projections of the plasma membrane that increase the surface area available for absorption

Cytoplasm

The cell’s region between the plasma membrane and the nuclear envelope. 70-80% water, semi-solid consistency,

cytosol

Nucleus

Houses the host cells DNA and directs synethesis of ribosomes and proteins.

Nuclear Envelope

Double membrane structure that constitutes the nucleus’ outermost portion, both the inner and outer membranes are phospholipid bilayers

Nucleoplasm

Semi-solid fluid inside the nucleus

Chromosomes

Structures within the nucleus made up of DNA. Every eukaryotic species has a specific number of chromosomes in the nucleus of each cell.

Chromatin

The unwound protein-chromosome complexes that makes up chromosomes when condensed and desondensed.

Nucleolus

Aggregates ribosomal RNA with associated proteins to assemble ribosomal subunits.

Ribosomes

• Responsible for protein synthesis.

• Consist of two subunits; large and small

• Attach to: Plasma membranes cytoplasmic side, ER’s cytoplasmic side, nuclear envelope outer membrane.

• Freely float as single units or polyribosomes

Polyribosomes

clusters of ribosomes

How do ribosomes receive their orders?

1. DNA within the nucleus transcribes into messenger RNA (m-RNA)

2. m-RNA travels to ribosomes which translate the code

3. Ribosomes then assemble amino acids into proteins during protein synthesis

Where are ribosomes particularly abundant?

Cells that synthesize large amounts of protein

• Pancreas - digestive enzymes

Mitochondria

• Responsible for making adenosine triphosphate, the cells main energy carrying molecule

• Oval shaped, double membrane organelles

• Contain separate DNA and ribosomes

• Each membrane is a phospholipid bilayer embedded with proteins.

• Inner folds called cristae which increase surface area

• Area inside cristae is the matrix

What is ATP (Adenosine Triphosphate)?

The cells main energy carrying molecule. ATP represents the cell’s short term stored energy.

What is cellular respiration?

• The process of making ATP using the chemical energy in glucose and other nutrients.

• Uses oxygen and produces carbon dioxide as a waste product.

Which cells have a high concentration of mitochondria?

Muscle cells, because muscles require a lot of energy.

What happens when cells don’t get enough oxygen?

They do not produce much ATP, and instead produce lactic acid in the absence of oxygen.

Peroxisomes

• Small round organelles enclosed by single membranes

• Responsible for breaking down fatty acids and amino acids using oxidation reactions

• Detoxify poisons

• Releases hydrogen peroxide (H2O2), but contains enzymes that safely break down H2O2.

Glyoxysomes

Specialized peroxisomes in plants that convert stored fats into sugars

Vesicles

• Membrane-bound sacs that function in storage and transport

• Does fuse with the membranes of other cellular components

Vacuole

• Membrane-bound sacs that function in storage and transport

• Does not fuse with the membranes of other cellular components

Centrosome

• The organelle where all microtubules originate

• Microtubule organizing center (MTOC) found near the nuclei of animal cells.

• Contains a pair of centrioles (perpendicular to each other)

• Each centriole is a cylinder of nine triplets of microtubules held together by nontubulin

Lysosomes

• The cells “garbage disposal”, using enzymes to break down proteins, polysaccharides, lipids, nucleic acids, and worn-out organelles.

• Very acidic 4.5-5pH

What is peptidoglycan?

Primary component of prokaryote cell walls.

What is cellulose?

A polysaccharide comprised of glucose units.

What is photosynthesis?

A series of reactions that use carbon dioxide, water, and light energy to make glucose and oxygen.

What is an autotroph?

An organism capable of making its own food.

What is a heterotroph?

An organism that must ingest their food.

What is a chloroplast comprised of?

1. Outer membrane

2. Intermembrane space

3. Inner membrane

4. Stroma

5. Granum

6. Thylakoid

What is a chloroplast responsible for?

Conducting photosynthesis to create the sugars used in cellular respiration to provide ATP energy generated in the plant mitochondria.

What is chlorophyll?

Green pigment that captures light energy that drives the reactions of photosynthesis.

What is endosymbiosis?

A mutually beneficial relationship in which one organism lives inside another.

Example: Microbes in the human gut that produce vitamin K.

What is symbiosis?

A relationship in which two separate species depend on each other for survival.

What does the Central Vacuole do?

Regulates the cells concentration of water in changing environmental conditions.

What does the endomembrane system do?

A group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.

What makes up the endomembrane system?

1. nuclear envelope

2. lysosomes

3. vesicles

4. endoplasmic reticulum

5. golgi apparatus

6. *technically the plasma membrane

What is the endoplasmic reticulum?

A series of interconnected membranous sacs and tubules that modify proteins and synthesize lipids

Where does protein synthesis occur?

In the rough endoplasmic reticulum

Where does lipid synthesis occur?

In the smooth endoplasmic reticulum.

What is the ER tubules’ hollow portion?

Lumen or cisternal space

What is the relationship of the ER and the nuclear envelope?

The ER’s membrane is continuous with the nuclear envelope.

What happens to proteins in the RER lumen?

They undergo folding or acquire side chains.

Where is the RER abundant?

In cells that secrete proteins such as the liver?

What is the SER (smooth endoplasmic reticulum) function?

• Synthesis of:

1. Carbohydrates

2. Lipids

3. Steroid hormones

• Detoxification of medications and poisons

• Storing calcium ions

What is the sarcoplasmic reticulum?

A specialized smooth endoplasmic reticulum found in muscle cells responsible for storing calcium ions needed to trigger coordinated contractions.

What is the golgi apparatus?

The organelle that tags, packs, and distributes lipids and proteins.

What is the side of the golgi apparatus closer to the ER?

The cis face

What is the side of the golgi apparatus farthest from the ER?

The trans face

What is the most common modificaton that happens in the golgi apparatus?

The addition of short sugar molecule chains

Where are golgi apparatuses most abundant?

• In secretory cells such as salivary gland cells

• In cells that secrete digestive enzymes

• In immune cells that secrete antibodies

What is the additional role of the golgie apparatus in plant cells?

Synthesizing polysaccharides

What is the process of phagocytosis?

1. Plasma membrane invaginates (folds in) to engulf a pathogen

2. The invaginated section pinches of and becomes a vesicle inside the macrophage

3. A lysosome fuses to the vesicle and uses hydrolytic enzymes to destroy the pathogen

What is the role of the cytoskeleton?

1. Maintain cell shape

2. secure organelles in position

3. Allow cytoplasm and vesicles to move withing the cell

4. Enables multicellular organisms to move

What three types of fibers make up the cytoskeleton?

1. microfilaments

2. intermediate filaments

3. microtubules

What are the characteristics of Microfilaments (actin filaments)?

1. Narrowest of cytoskeleton fibers

2. Function in cellular movement

3. diameter ~7nm

   1. Comprised of 2 globular protein intertwined stands called actin

What is the relationship between actin and myosin?

Actin serves as a track for the motor protein myosin

Where are actin and myosin plentiful?

In muscle cells where they slide past each other

What characteristic of microfilaments enables a cell to change chape and move?

Microfilaments can depolymerize (disassemble) and reform quickly.

What is the role of intermediate filaments?

• Bear tension to maintain cell shape

• Anchor the nucleus and other organelles in place