Cytology

What is the basic structural and functional unit of the body?

The cell

What are the 2 basic cell types and how are they different?

Eukaryotic and Prokaryotic

What are the 3 main components of cells?

They have plasma membrane, cytoplasm, and a nucleus

What are the basic components of the cell membrane?

Phospholipid bilayer with proteins

 What are other names for the cell membrane?

Plasma membrane and Plasmalemma

What is the characteristic appearance of the cell membrane in the electron microscope?

It has a trilaminar appearance (meaning it looks like 3 layers when it’s really 2 cell membranes close to one another)

What are the functions of the cell membrane?

• Creates a physical barrier

• Selective permeability: regulates entry/exit of ions, nutrients, and waste

• Establishes an electrochemical gradient: establishes/maintains an electrical charge difference across the membrane

• Communication

What comprises about 75% of the cell membrane?

Phospholipids

What does the term amphipathic mean?

Has one hydrophilic/polar head and one hydrophobic/non-polar head

What role does cholesterol play in the cell membrane?

Restricts movement of phospholipids modulating fluidity

Describe integral proteins and peripheral proteins.

Integral proteins: penetrates into the membrane

Peripheral proteins: do not penetrate the membrane

Which 2 molecules contribute to the glycocalyx?

Oligosaccharides and proteins

What are the functions of the membrane proteins?

Determines primary functions

What are the 3 types of endocytosis?

• Phagocytosis: vesicles are formed as particulate materials external to the cell are engulfed by pseudopodia (eat cells)

• Pinocytosis: vesicles are formed as interstitial fluid is taken up by the cell (cell drinking)

• Receptor-mediated endocytosis: plasma membrane receptors first bind specific substance then both receptor and substance are taken up by the cell

What is endocytosis?

Bulk movement of substances INTO the cell by vesicles forming at the plasma membrane

What is exocytosis?

Bulk movement of substance OUT of the cell by fusion of secretory vesicles with the plasma membrane

Describe the electrochemical gradient.

Inside of the cell is negative compared to the outside of the cell which is positive

What is signal transduction and what type of molecules are involved in it?

Communication between cells via extracellular molecule or physical stimuli

• There’s 3 different kinds: channel-linked receptors, enzymatic receptors, g protein-coupled receptors

• They each involve ligands and enzymatic reaction involves enzymes and phosphate and g protein-coupled involves GTP and effector proteins as well

What is the cytosol?

Fluid portion of the cytoplasm. It contains organelles, nutrients, ions, enzymes, gases, and waste products

What are ribosomes composed of and what is their function?

Composed of rRNA and proteins. Function is that their the site of protein synthesis

What is rough endoplasmic reticulum (rER) and what is its function?

It is a membranous network that extends from the nucleus and has ribosomes

• Function: accepts proteins from ribosomes, begins glycosylation as well as other post-translational modifications, then transfers them to the golgi apparatus

Where would we see a lot of rER?

Cells that specialize in protein synthesis

What is smooth endoplasmic reticulum (sER) and what is its function?

It is a membranous network that is continuous with rER but doesn’t have ribosomes; usually further off nucleus

• Function: synthesis of phospholipids and steroids, detoxification of alcohol and drugs, calcium storage and release

What is the Golgi apparatus and what is its function?

It is where the ER sends proteins

Function: completes post-translational modifications of proteins produced in rER then it packages the proteins (secretory vesicle), and forms lysomoses

What are lysosomes and what are their functions?

Membranous vesicles containing about 40 hydrolytic enzymes that can break down molecules

• Function: sites of intracellular digestion and turnover of cellular components; also function in autophagy AKA eating worn out cells so new ones can be made

What are proteasomes and what is their function?

Large protein complex inside cell

• Function: degrade denatured or other nonfunctional proteins and removes proteins no longer needed ****Only do proteins, lysosomes do full cell

Describe the structure of the mitochondrion.

Double membraned organelle with a smooth outer membrane and highly folded inner membrane (fold called cristae)

What is the function of the mitochondria?

Cells powerhouse; contains enzymes necessary for aerobic cellular respiration and the production of ATP, determines how much of something that's needed in the cell

Which organelle has its own DNA and ribosomes?

Mitochondria

 What are peroxisomes and what is their function?

Membrane bound vesicle containing oxidative enzymes

• Function: produces and degrades H2O2, can inactivate some toxic molecules, and performs reactions involved in formation of bile acids and cholesterol

What is the cytoskeleton and what is its function?

An array of protein filaments aka cell skeleton

• Function: determines the shape of the cell, movement of organelles and vesicles, and in some cases movement of the entire cell

What are the 3 protein filaments that make up the cytoskeleton?

Microtubules (largest), microfilaments, intermediate filaments (smallest)

What are microtubules made of and what functions do they perform?

Made of: tubulin which is globular protein

Functions: helps to maintain cell shape and also involved in movement of organelles, vesicles, and macromolecular complexes

What organelles have microtubules as part of their structure?

Mitotic spindle, centrioles, cilia, and flagella

What are centrioles composed of and what is the arrangement? What are their functions?

Made of: 9 triplets of microtubules

Functions: cell division (mitosis) and spindle formation

What are cilia composed of and what is the arrangement? What is its function?

Made of: 9 peripheral doublets on the edge and 2 central singlets in the center “9+2” array

Function: used to move mucus in the respiratory system and the ovum in the female reproductive system (like an oar in a boat)

What are flagella composed of and what is the arrangement? What is its function?

Made of: “9+2” array BUT longer

Function: Propels sperm during swimming

Microfilaments are composed of what protein?

Actin

What roles or functions are microfilaments involved in?

During muscle contraction the actin interacts with myosin and in cell division, forms cleavage furrow

Give examples of intermediate filaments and what are their functions?

Examples: keratins, vimentin, neurofilament, lamins

Function: help to maintain cell shape and anchor the nucleus and other organelles

What are inclusions and list some common ones.

Temporary structures of metabolites or other substances

Common: lipid droplets in adipocytes, glycogen granules, pigments (melanin, lipofusion)

What is the nucleus and what does it consist of?

Command center of the cell and it consists of nuclear envelope, chromatin, nucleoli

 Describe the nuclear envelope and what is its purpose?

Double membrane with a space in between, outer is continuous with rER and inner is the nuclear lamina (stability). The 2 membranes are bridged by nuclear pore complexes 

Purpose: regulates movement of macromolecules

What is the difference between chromatin and chromosomes?

Chromatin is the base of double-stranded DNA helix and chromosomes are densely packed together chromatin

What does the term diploid mean? Haploid?

Diploid: 2 copies of each or paired

Haploid: one copy or unpaired

How many chromosomes do human cells have?

46 chromosomes, 23 pairs

What is euchromatin? Heterochromatin?

Euchromation: structural state of chromatin more open structure because its actively being transcribed

Heterochromatin: structural state of chromatin more compacted little to no transcription is occurring

What is a karyotype and what is it used for?

Microscopic analysis of chromosomes used in screening for genetic disease

What are the events in the cell cycle?

Interphase, mitosis, cytokinesis

What are the 3 stages of interphase and what happens in each?

G1: growth phase, cellular contents, excluding the chromosomes, are duplicated

S: each of the 46 chromosomes is duplicated by the cell

G2: the cell double checks the duplicated chromosomes for error, making any repairs needed

What is the G0 phase and what cells are in this stage?

Where the cells are resting from division. Cells that stay in this stage are ones that are terminally differentiated like cardiac muscle and nerve cells

What is mitosis?

Somatic cells where parent cells have 46 chromosomes and daughter cells each have 46 chromosomes. This happens in most places in the body

What is meiosis?

germ cells where parent cells have 46 chromosomes and daughter cells have 23 chromosomes (called reduction division)

What are the 4 stages of mitosis?

Prophase, metaphase, anaphase, telophase

What is prophase?

nucleolus and nuclear envelope disappears, chromatin condenses into chromosomes, centrioles migrate to opposite poles and form mitotic spindle

What is metaphase?

paired chromosomes line up at the equatorial (metaphasal) plate (shortest stage)

What is anaphase?

separation! Sister chromatids are separated toward opposite poles, development of cleavage furrow!!

What is telophase?

mitotic spindle disappears, chromosomes revert to chromatin, nuclear envelope and nucleus reforms

What is cytokinesis and when does it begin?

Where the cleavage furrow deepens until it separates into 2 daughter cells

Begins: late anaphase and finishes shortly after telophase

What is the main difference between mitosis and meiosis?

Meiosis is the same 4 steps of mitosis except it happens twice to give cells genetic diversity

 What is a totipotent cell?

A cell that can become any cell in the body

What is a pluripotent cell and what does it give rise to?

A cell that has started differentiating, can't give you ANY cell

 What is a multipotent cell?

A cell that can differentiate into more than one type of cell but only from a closely related family of cells

What is apoptosis and what is the basic process?

Cell suicide, when its not really doing its job

Process: cytoplasmic proteins regulates the cell then simulates lysosomes to release and phagocytic cells do their thing

What are the 3 germ layers and what basic tissues does each give rise to?

Ectoderm: skin, nervous system

Mesoderm: connective tissue, muscle

Endoderm: lining tissue, GI tract, etc.

What is a tissue?

Group of cells joined together to perform a specific function

What are the 4 basic kinds of tissue?

nervous, epithelial, muscle, connective

What is the stroma?

supporting tissue

What is the parenchyma?

functional tissue of organ