chapter 6 (tour of the cell)

What is the significance of The Cell and Microscopy?

The Microscope ("small view") is has been the most important technological tool in biology

has been the most important technological tool in biology

What are the three things Microscopes accomplish?

1. They magnify Images. 2. They resolve images or make them clearer. 3. They can provide contrast to study certain cell components

What is the unit of measurement micrometer $(\mu)$?

One millionth of a meter (used for typical cell sizes)

What is the unit of measurement nanometer (nm)?

One billionth of a meter (used for electron microscopy)

What is the typical diameter range for most plant and animal cells?

Between 10-100 nm in diameter

What is the typical size range for most cell components?

Between 1-10 nm in size

Who coined the term "cell" and when?

Robert Hooke in 1665 after observing the first cells

What did Robert Hooke actually see?

LM (Light Microscopes) can magnify images up to about 1,000X and show dynamic cell processes in action, such as cell division

What are Electron Microscopes?

Microscopes (such as SEM or Scanning and TEM or Transmission types) that can take us down into the nm range of measurement

How do SEM and TEM microscopes differ?

SEM reveals the **surface 3D shape** of the sample; TEM reveals the internal structure of the sample

What is a key difference in sample preparation between LM and Electron Microscopes?

For Electron Microscopes, the samples must be killed

What is a Micrograph?

A photograph taken through a microscope

Our eyes can only resolve images down to about .1mm. What does this mean?

Resolution is the ability to distinguish two close objects as separate; microscopes improve this ability beyond the limits of the human eye

What is Cell Fractionation?

The process of preparing cells and their components for microscopy

What are the components of a typical Prokaryotic cell?

Flagella, capsule, chromosome, cell wall, ribosomes, nucleoid, etc.

What is the primary focus of study after reviewing prokaryotes vs. eukaryotes?

The Eukaryotic Cell

What is another name for the cell or plasma membrane?

The "brain" of the cell

Why is the plasma membrane important in animals?

This structure defines the cell by creating a border with the environment

What are the primary constituents of the plasma membrane?

Phospholipids

What is the function of the phospholipids in the membrane?

They provide selective or semi-permeability to the membrane

Why are cells typically small?

To increase the surface area to volume ratio, which allows for enhanced communication and better control of activities

What are the components of the Nucleus?

It is the compartmentalization in eukaryotic cells. It contains the double membrane nuclear envelope, the inner and outer membranes and intermembrane space, the nuclear lamina (intermediate filaments), nuclear pores, cytoplasm to the outside and nucleoplasm inside; it also houses the nucleolus with rRNA, ribosomes, chromatin vs. chromosomes (the attachment of rough ER)

What is the function of Ribosomes?

The sites of protein synthesis, composed of a small and large subunit; they may be free or bound

What is the Endoplasmic Reticulum (ER)?

A system of extensive internal or endomembrane system, the major component being RER or SER

What is the difference between Rough ER (RER) and Smooth ER (SER)?

The RER is studded with ribosomes and is contiguous with the outer nuclear envelope (functionally continuous with the transport vesicles

taxis); the SER is smooth and contains no ribosomes; it is found in the liver and muscles

What are the functions of the RER?

It is involved with the Golgi Apparatus and secretory proteins

What are the functions of the SER?

It is used to detoxify drugs and alcohol, store calcium, and make lipids and metabolize carbohydrates (can contain tubular sacs called Cisternae)

What is the Golgi Apparatus?

Looks like a pita bread and consists of many membranes pressed together; it has a Cis or receiving side for transport vesicles carrying proteins, and a shipping side called a Trans side for sending those proteins via transport vesicles to other parts of the cell

How is the Golgi Apparatus like the "Post Office" of the cell?

It processes, refines, sorts, ships, and tags (chemically modified and labeled) proteins

What are Lysosomes?

Membrane bound sacs with hydrolytic enzymes; they function as digestive compartments (for phagocytosis in protozoans) and autophagy (development, such as tadpole to frog)

What is the Large Central Vacuole in plants and what is its purpose?

It is the largest organelle and functions as the Food Vacuole and Contractile Vacuole in Protozoa; it is a central part of the endomembrane system

What are the two types of Energy Transformers of the cell?

The Mitochondria and Chloroplasts

What is the unique characteristic of the Mitochondria and Chloroplasts?

They are large, double membrane organelles that possess their own DNA and ribosomes

Why are they similar (Lynn Margulus ca. 1985 proposed the Endosymbiotic Theory for eukaryotic cells)?

They both share the characteristic that they are large, double membrane organelles that possess their own DNA and ribosomes

Describe the Mitochondria (pl.)

Mitochondrion (s.).

It is the site of aerobic cellular respiration; it has inner and outer membranes, intermembrane space, ribosomes, DNA, matrix (fluid inside inner membrane) and a cristae (folds in inner membrane)

Describe the Chloroplasts (pl.)

Chloroplast (s.).

The site of photosynthesis; it has inner and outer membranes, stroma (fluid, site of the Dark Reactions), thylakoids (green with chlorophyll, site of the Light Reactions), grana (many stacks of thylakoid membranes)

What is the general category of Plant Plastids besides the chloroplasts?

Chromoplasts (color) and Amyloplasts (starch storage)

What are Peroxisomes?

Organelles often found next to chloroplasts and mitochondria

What toxic byproduct do Peroxisomes produce and how do they deal with it?

They produce Hydrogen Peroxide ($\text{H}2\text{O}2$) and use the enzyme catalase to convert $\text{H}2\text{O}2$ to water and oxygen; $\text{H}2\text{O}2$ is stored at 8% toxic, but at 3% safe concentration to store

What is the Cell Cytoskeleton?

A network of proteins including the Microtubules, Intermediate Filaments and Microfilaments; it supports and provides motility functions

What are Microtubules?

Hollow tubes of protein, consist of the protein tubulin in dimer form; 25nm diameter; responsible for cell shape, motility (cilia and flagella), chromosome and cell organelle movements; they form the basal body of Cilia and Flagella and the Centrioles (from the Centrosome)

Describe the arrangement of microtubules in Cilia and Flagella.

A total of 9 triplet microtubules circle the two single microtubules in Centrioles and Basal Body, but for Cilia and Flagella, it's a $9+2$ arrangement of doublets surrounding a pair (a total of 20 microtubules)

How do cilia and flagella differ?

Cilia are typically shorter and more numerous, moving with a back-and-forth or oar-like motion; Flagella are usually longer and fewer, moving with a whip-like motion

What are Microfilaments?

Solid rods of 2 actin filaments; 7nm in diameter; responsible for cell shape, cytoplasmic streaming, muscle contraction (actin and myosin)

What are Intermediate Filaments?

Include combinations of several different proteins such as keratin and others; coiled into cables about 8-12 nm in diameter; these anchor cell organelles and comprise the nuclear lamina

What is the main component of the Cell Wall in plants?

Cellulose and Pectin (glue); it is a primary structure, but a secondary wall may form

What is the ECM (Extracellular Matrix) of animal cells?

Includes collagen protein, fibronectin protein, proteoglycans (protein + carbohydrates), and integrins; it is the substance that holds the animal cells together outside the cell membrane, the "skeleton" of animal cells

What is a cellular fingerprint and what is its purpose?

Glycoproteins and glycolipids on the cell surface; it's used for communication, transport, and protection and is necessary for cell-cell recognition

What is the Plasmodesmata?

A **communication

transit junction** in animals we have the Gap Junctions which act as a better choice

How do cells in the small intestine of animals adhere?

They use Tight Junctions which act as nails or rivets

How do cells connect and function in the heart?

They use Anchoring Junctions which provide connections between cells and communication