Chapter 4 principles of bio

define cells

the fundamental unit of life

What is the cell theory?

-cells are the fundamental unit of life

-all organisms are composed of cells

-all cells come from preexisting cells

What does the cell theory imply?

-functions of cells are similar

-life is continuous (produce next generation)

-origin of life was the origin of cells

Cells are able to maintain..

homeostasis

Define the plasma membrane

acts as a thin, flexible barrier surrounding the cell. has selective permeability (picks what comes in and goes out) but still protects its insides from the environment

The organization and basic functions of all cells are…

similar

the scale of life

cells are small because…

a high surface area-to-volume ratio is needed

What does the cell surface area do for both resources and wastes?

limits exchange with the environment

Which two people were the earliest to describe cells?

Robert Hooke and Antoni van Leeuwenhoek

What century were microscopes sufficiently developed for biologists to seriously study cells?

late 19th century

How do we study small cells?

microscopes

What two things can microscopes do to images?

magnify and resolve

describe magnification in microscopes

increases apparent size

describe resolution in microscopes

a measure of the clarity of magnified object

What are the two types of microscopes that we can use? define both

-Light microscopes: use glass lenses and refracted light

-Electron microscopes: electromagnets focus an electron beam (greater magnification)

What are the pros of electron microscopes?

magnifies up to 100,000 times, allowing visualization of small cells and organelles

What are the cons of electron microscopes?

expensive and can not be used to observe living samples

When was an electron microscope first used?

1950s

what are the two types of electron microscopes? what is the difference between the two?

-scanning electron microscope (SEM): study the details of cell surfaces (outside surface)

-transmission electron microscope (TEM): study the details of internal cell structure

What are the two prokaryotic cells?

Bacteria and Archaea

What do prokaryotes NOT have?

they do not have a membrane-bound nucleus or organelles

Define prokaryotic cells

-very small

-can be single cells but often form chains or clusters (ex. strep forms chains)

What are some features of prokaryotic cells?

-enclosed by a plasma membrane

-DNA in a region called the nucleoid

-contain ribosomes, RNA and protein complexes; sites of synthesis

-contain cytoplasm, which consists of cytosol plus filaments and particles

-have a cytoskeleton, a system of protein filaments that maintain cell shape

-could contain storage granules

What characterizes the outer surface of prokaryotes?

• rigid cell wall outside plasma membrane

• some bacteria have a slimy capsule of polysaccharides

• some prokaryotes swim by flagella (long almost hair looking)

bacterial cells walls contain…

peptidoglycan

some bacteria have an additional…

outer membrane

prokaryotes are…

very diverse and important

All other forms of life (eukarya domain) iare composed of…

eukaryotic cells

Eukaryotes have organized and specialized membrane-bound-.1.- and membrane bound -.2.-

1. organelles

2. nucleus

membrane-bound compartments allow for…

“division of labor”

the nucleus is the cells…

control center

what does the nucleus contain?

DNA

The nucleus is the site of…

1. site of DNA replication

2. site where gene transcription is turned on or off

assembly of ribosomes begins in a region called…

the nuleolus (usually looks like a darker spot)

The nucleus is surrounded by what?

the nuclear envelope

describe the nuclear envelope

an outer, double membrane that contains nuclear pores

Ribosomes are sites of… that occur in both…

protein synthesis, prokaryotic and eukaryotic cells

ribosomes consist of… and more than… different protein molecules

• ribosomal RNA (rRNA)

• 50

In eukaryotes, ribosomes can be:

• free in the cytoplasm

• attached to the endoplasmic reticulum

• inside mitochondria and chloroplasts

Describe the endomembrane system

a network of organelles that exchange materials through small membrane-enclosed transport vesicles

What does the endomembrane system include?

• the plasma membrane

• nuclear envelope

• endoplasmic reticulum

• golgi apparatus

• lysosomes

describe the Endoplasmic Reticulum (ER); what does it make up?

network of interconnected membranes; makes up nuclear envelope

what is attached to the Rough Endoplasmic Reticulum (RER)?

ribosomes

what is made in the RER? what is the process?

newly made secreted and membrane proteins are made here; they enter the RER lumen, are modified and folded, are transported to other regions

What makes the Smooth Endoplasmic Reticulum (SER) different from the (RER)?

more tubular and don’t have ribosomes attached

What are the functions of the SER?

• chemically modify small molecules (ex. drugs and pesticides)

• Synthesis of lipids and cholesterol, and other steroids

• Site of glycogen degradation in animal cells (break down glycogen and release glucose into circulation)

• helps detox

what is the golgi apparatus composed of?

flattened sacs (called cisternae) and small membrane-enclosed vesicles

what is the function of the golgi apparatus?

(basically ships and receives proteins)

• receives proteins from RER- can further modify them

• concentrates, packages, sores and processes proteins

what does cis face and trans face mean?

• the cis face: entry surface

• the trans face: exit surface

what does the cis region do vs. the trans region?

• cis region: receives vesicles from the ER (closest to RER)

• trans region: vesicles bud off (closest to plasma membrane)

what are the properties of lysosomes?

• what are primary lysosomes and what do they do?

• what happens next?

• what happens during the last step? what do they form?

• sac of digestive enzymes in animal cells which hydrolyze macromolecules into monomers.

• food molecules enter the cell by phagocytosis

• phagosomes fuse with primary lysosomes to form secondary lysosomes where enzymes hydrolyze the food

• this creates perfect conditions to break down

where are vacuoles most commonly found?

in plants, fungi, and protists

describe a vacuole compared to a vesicle

• vacuoles are large and stay in place

• vesicles are smaller and move around

plant central vacuoles are similar to…? why

lysosomes because they break down and store wastes and toxic compounds

what are the main functions of vacuoles?

• provide structure for plant cells

• store some pigments and digestive enzymes

• store waste and toxic compounds

food vacuoles in protists fuse with … to digest food

lysosomes

freshwater protists may have … to expel excess water

contractile vacuoles (contract and push out excess water)

what do peroxisomes do and what do they contain?

• metabolize small organic compounds

• membranous sac containing enzymes that help transfer hydrogen from other compounds to oxygen

what are some functions of peroxisomes?

• break down fatty acid molecules

• synthesize phospholipids

• degrade alcohol in yeast cells and detoxify toxic compounds in human liver and kidney cells

what are the two energy converting organelles? what cells are each in?

• mitochondria- most eukaryotic cells

• chloroplasts- some plants and algal cells

what are energy converting organelles specialized to do? how do they do this?

• specialized to facilitate conversion of energy from one form to another

• chemical or light energy must be converted into more convenient forms like ATP

mitochondria and chloroplast have their own…

what is this theory?

ribosomes and DNA molecules

theory of serial endosymbiosis

what is the theory of endosymbiosis?

states that mitochondria and chloroplast were once independent, free-living bacteria that were swallowed by a larger host cell

in the mitochondria…

energy in fuel molecules is transformed to ATP (energy production)

how many membranes do mitochondria have? describe.

2, the inner membrane folds inward to form cristae (creates a large surface area)

what does the mitochondrial matrix contain?

enzymes, DNA, and ribosomes

define chloroplasts

• site of photosynthesis- light energy is converted to the energy of chemical bonds

how many membranes do chloroplasts have?

2 (double membrane)

chloroplast contains chlorophyll. define chlorophyll

• green pigment that’s traps light energy for photosynthesis

what does thylakoids contain

contain chlorophyll and other pigments that harvest light energy

what are thylakoids?

circular compartments of the inner membrane

define grana

stacks of thylakoids

define stroma

fluid in which grana are suspended

what is one type of plastids that occur only in plants and some protists?

chloroplasts

other plastids contain…

• chromaplasts- contain red, orange, and yellow pigments

• leuciplasts- like amyloplasts, store starches and fats

the cytoskeleton contains which 3 components? (in order from largest to smallest)

• microtubules

• intermediate filaments

• microfilaments

describe microtubules (function, consist of)

• function- structure and in movement of chromosomes during cell division

• track (acts as railway for cells) for intracellular movement and structural components of cilia and flagella

• consists of two forms of protein: alpha-tubulin and beta-tubulin; combine to make a dimer

why are cilia and flagella helpful?

help unicellular and small multicellular organisms move through a watery environment

cells use cilia to move…

liquids and particles across cell surface

describe intermediate filaments

• tough, flexible fiber about 10 nm in diameter

function of intermediate filaments, what group have intermediate filaments

• provide mechanical strength (anchor materials) and help stabilize cell shape

• only some animal groups

intermediate filaments include…

keratinsbin vertebrae epithelial cells and neurofilaments in nerve cells

describe microfilaments

what they consist of and how they are linked

• flexible, solid fibers about 7 nm in diameter

• consists of two intertwined polymer chains of beadlike actin molecules

• linker proteins

microfilaments bundles provide…

what do they form and where?

• support for cell structures

• form the cell cortex, inside plasma membrane

microfilaments generate…by what?

movement by rapidly assembling and disassembling

microfilaments contain muscle cells that have two types of specialized filaments. what are they?

actin and myosin

• ATP, actin and myosin help contract muscles

in amoeba and human WBC, actin filaments push the plasma membrane outward by forming…

pseudopodia (microfilaments get longer and push into environment)

cell coverings: many cells are surrounded by a…

glycocalyx (extension of material in membrane)

what are the functions of cell coverings?

• allows cells to recognize one another, make contact, and form adhesive or communicating associations

• contributes to the mechanical strength of multicellular tissues

what are cell coverings formed by?

polysaccharide side chains of proteins and lipids within the membrane

what do many animal cells secrete? what does this consist of?

• extracellular matrix (secreted material, not directly attached)

• a gel of carbohydrates and fibrous proteins (mainly collagen)

functions of extracellular matrix

• holds cells together in tissues and contributes to tissue properties

• filters materials passing between different tissues

• plays a role in chemical signaling

the cells of most bacteria, archaea, fungi, and plants are surrounded by

a cell wall (rigid outer structure and additional protective layer)

plant cell walls contain…

cellulose

a growing plant…, which either solidifies or replaced by… with a different chemical composition

• primary cell wall

• secondary cell wall