Lecture Slides 2 - Cells

Cytology

The study of cells; uses microscopes

Cell size unit

Micrometers (µm); 1 cm = 10,000 µm

Cell size range

From about 7 µm (red blood cell) to 20 µm (oocyte)

Cell (definition)

The basic unit of life, containing all components necessary for survival

Three main cell parts

Membrane, cytoplasm, and nucleus

Cell membrane (plasma membrane)

Surrounds the cell and controls what enters and exits

Phospholipid bilayer

Two layers of phospholipids forming the basic framework of the cell membrane

Hydrophilic heads

Face outward, toward water, in the phospholipid bilayer

Hydrophobic tails

Face inward, away from water, in the phospholipid bilayer

Fluid mosaic model

Describes the cell membrane as a fluid, ever-changing structure containing proteins, cholesterol, and carbohydrates

Integral proteins

Membrane proteins that span the entire membrane

Peripheral proteins

Membrane proteins that attach to the membrane surface

Intracellular fluid

Fluid found inside the cell

Extracellular fluid

Fluid found outside the cell

Interstitial fluid

Extracellular fluid located between cells

Cystic fibrosis

Disease caused by a defective CFTR chloride ion channel protein; leads to thick, sticky mucus in the lungs

Microvilli

Extensions of the plasma membrane with no motion; increase surface area (e.g., for absorption)

Cilia

Extensions of the plasma membrane that move objects across the cell surface

Flagella

Extensions of the plasma membrane that propel a cell

Cytoplasm

Contains the cytosol and all organelles except the nucleus; site of most cellular activities

Cytosol

The jelly-like fluid that fills the cell

Organelles

Specialized structures within the cell, each with unique functions (like organs of the body)

Endoplasmic reticulum (ER)

Network of membranes involved in protein and lipid synthesis

Rough ER (RER)

ER studded with ribosomes; synthesizes proteins for the membrane, export, and lysosomes

Smooth ER (SER)

ER without ribosomes; synthesizes lipids/steroid hormones, stores/regulates Ca2+, and performs detoxification

Ribosomes

Site of protein synthesis; can be free in the cytosol or attached to the RER

Free ribosomes

Make proteins that stay within the cytosol

Golgi apparatus

Modifies, sorts, and packages proteins and lipids for storage or transport; made of stacked flattened sacs

Lysosomes

Contain enzymes that digest and recycle cellular waste, damaged organelles, and foreign invaders ("garbagemen")

Mitochondria

Generate ATP through cellular respiration; have a double membrane with inner folds called cristae ("powerhouse")

Cristae

Folds of the inner mitochondrial membrane where cellular respiration occurs

Peroxisomes

Contain enzymes that neutralize toxins, converting harmful byproducts into water and oxygen ("detoxifiers")

Cytoskeleton

Provides structural support and facilitates cell movement

Microfilaments

Cytoskeleton component made of actin

Intermediate filaments

Cytoskeleton component made of fibrous subunits (e.g., keratins)

Microtubules

Cytoskeleton component forming cilia, flagella, and centrioles

Centrioles

Origin point where tubulin subunits are added to build microtubules

Inclusions

Diverse group of chemical substances some cells store temporarily

Melanin

A pigment inclusion found in skin, eye, and hair cells

Lipid droplets

Inclusions representing fat stores in liver and fat cells

Glycosomes (glycogen)

Inclusions representing stored carbohydrates in liver and skeletal muscle cells

Nucleus

The "brain"/command center of the cell; houses DNA, surrounded by the nuclear envelope

Nuclear envelope

Double membrane with a fluid space in between, surrounding the nucleus

Nuclear pores

Tiny passageways allowing exchange of materials between the nucleus and cytoplasm

Nucleolus

Structure inside the nucleus responsible for manufacturing RNA for ribosomes

Chromatin

Loosely coiled DNA-protein material found in the nucleus

Selective permeability

Property of the cell membrane that regulates which substances can pass through