Bio 251 Lec Exam 2

2 fundamental types of cell

-eukaryotic
-prokaryotic

Eukaryotic cell

-uni- and multicellular
-10-100 micrometers
-exhibit a HIGH level of diversity of cell shape

Prokaryotic cell

-bacteria: almost all are unicellular
-archaea: ALL are unicellular
-1-10 micrometers
-exhibit a low level of diversity of cell shape

Structures common to ALL cells (5)

-plasma membrane
-cytoplasm
-chromosomes
-ribosomes
-cytoskeleton

Biological membrane made of

phospholipids

Structure of biological membrane

-2 layers of phospholipids
-proteins
-polysaccharides

Function of plasma membrane

-surrounds the cell
-permits some molecules to enter the cell and some molecules to leave the cell
-maintains UNEQUAL distribution of ions/molecules

Extracellular face

net positive

Cytoplasmic face

net negative

Define cytoplasm and function

-the liquid portion of the cell
-MOST biochemical reactions take place in the cytoplasm, ceasing in a sufficiently dehydrated cytoplasm

Chromosomes

1 molecule of DNA and millions of proteins

Prokaryotic chromosomes

-no membrane bound nuclei
-usually posses one circular chromosome

Eukaryotic chromosomes

-posses membrane bound nuclei
-posses multiple linear chromosomes

Cyotoskeleton

fibers of many protein molecules (non-covalently attached to each other)

T/F ALL cytoskeletons are in the cytoplasm

True

Functions of ALL macro-world skeletons and cytoskeletons

-structure
-protections
-support
-movement

Non-universal structures (9)

-cell wall
-cell capsule
-slime layer
-plasmid
-organelle
-flagella
-archaella
-cilia
-pili

Cell wall structure and function

-rigid yet flexible structure that completely surrounds a cell
-made of varied polysaccharides and proteins that support and protects the cell

T/F Polysaccharides of cell wall vary by cell class

True

Plant cell walls

majority polysaccharide-cellulose

Fungal cell walls

majority polysaccharide-chitin

Many eukaryotic cells

have cell walls

Some protist cells

have cell walls MOST don't

Many eukaryotic animal cells

do NOT have cell walls

Prokaryotic cells have cell walls

Bacteria: majority polysaccharide-peptidoglycan
Archaea: majority polysaccharide- psuedomurein or methanochondrotin

Structures built external to prokaryotic cell walls

-made of polysaccharides, proteins, lipids
-used for: protections, attachment to surfaces, formation of biofilms

Slime layer

-no clear boundary between slime layer and surrounding medium
-molecules of slime layer can diffuse into the surrounding medium

Capsule

-gel that has a clear boundary with the surrounding medium
-molecules of the capsule tend to remain part of the capsule

Plasmid

small circular molecule of DNA that usually includes at least one gene

What cells have plasmid?

-plant cells and fungal cells can also have plasmids
-prokaryotic cells can have zero to many plasmids
-a single prokaryotic cell can have different plasmids that hold different genes

Organells

a membrane-bound structure inside of a cell

What cells have organelles?

-MOST prokaryotic cells have no organelles but photosynthetic bacteria do
-eukaryotic cells have multiple organelles

Nucleus

organelle that holds linear chromosomes

Mitochondrion

transfers energy of electrons in glucose to electrons in ATP

Electron transport chain

involved in aerobic respiration

Circular DNA

mitochondrial DNA (mtDNA)

Chloroplast

captures light energy and stores it in electrons of electron-carrier molecules (NADPH)

T/F plants and MANY protists have chloroplasts

True

Thylakoid space

lumen of thylakoid

Why are thylakoids important?

they are within the membrane of the molecule that captures light energy

Granum

stacks of thylakoids

Lumen (lumina plural)

internal volume of a tubular space

Define endoplasmic reticulum and structure

-network of tubes, channels, and cisternae that aids in transportation
-constantly reshaped
-connected to the nuclear membrane; contiguous with the ER

Cisterna (cisternae plural)

natural or artificial receptacle for water

Rough ER structure/function

-intake, modification, and transport of newly synthesized proteins
-bumps on rough ER are ribosomes

Smooth ER function

-modification of small molecules
-steroid and lipid synthesis
-glycogen breakdown by hydrolysis

Vacuole structure/function

-an organelle that stores water and/or other molecules
-ALL eukaryotic cells have vacuoles; plant cells have largest vacuole

Golgi apparatus structure/function

-stacks of flattened sacks
-proteins from the RER are covalently modified and sorted; works as a conveyer belt processing proteins through the lumen

T/F proteins made by ribosomes are not in final form and need more modification

True

Lysosome structure/function

-an organelle that stored digestive enzymes
-phagocytosis of invading cells or diseased/dying self cells
-digestion of damaging organelles

Digestion

is the release of enzymes to break down food

Phagocyte

a cell that can internalize another cell (ex: human macrophage)

Phagocytosis

the act of a cell internalizing another cell

T/F cells consumed are destructed and materials of that cell can be recycled

True

Flagellum (flagella plural) definition

a long fiber that is made of many proteins, and used specifically for moving a bacterial cell through a liquid environment (longer than bacteria and can be counted)

Structure of flagella

filament, hook, and basal body

Filament

flexible structure that pushes against external fluid

Hook

curved structure that connects the filament to the basal body; hook can be rotated by the basal body

Basal body structure/function

-anchors flagellum to cell wall and plasma membrane; includes ring complexes and motor proteins
-L ring, P ring, MS ring, C ring

Archaellum structure/function

-a long flexible that is made of many proteins, and used specifically for moving an archaeon through a liquid environment
-comprises of a basal body and filament; SOME have hook structures not NOT always

Pilus (pili plural) structure/function

-fiber that is made of many proteins and extends outside of a prokaryotic cell
-pili used to attach to other cell or to surfaces and used for movements

How do pili movement work?

end of pili bind noncovalently to a surface and the cell pulls pili back into the cell

T/F bacteria pushes while pili pull

True

T/F Eukaryotic cells have flagellum but bacterial flagella are built differently

True

Cilia structure

shorter, more numerous versions of eukaryotic flagella (hundreds to thousands)

Microtubules structure

made of alpha tubulin-GTP; beta tubulin GDP

Structure of eukaryotic cilia or flagellum

outside: finger-like extension of the plasma membrane
-inside: a bundle of many microtubules

Eukaryotic cells use flagella to

push the cell through liquid

Eukaryotic cells use cilia to

push fluid along the surface of the cell AND pushing the cell through liquid

Amount of prokaryotic cells outnumber

the amount of Eukarya

Prokaryotes mostly live

-deep subsurface
-low-zero light or O2
-high temperature
-water

Prokaryotes living in the greatest variety of environments means

prokaryotes have the greatest variety of biochemical reactions

Bioaerosol

airborne bacteria, viruses, fungi, pollen, microalgae, protozoa, plant detritus, insert fragments, animal fur, and cell fragments resulting from natural and anthropogenic processes

Bioaerosol measure by

PM10 particular matter mass of diameter < 10 micrometers

Cyanobacteria contributes to environment

O2 to the atmosphere, and new organic molecules to the biosphere (known as photosynthetic archaea)

Prokaryotes contribute to environment

-MANY are decomposers
-SOME "fix" nitrogen; they take N2 from air/water and convert it into other molecules that other living systems can use; for example they convert NH4+ which can be used by plants to build amino acids

Decomposers

organisms that convert large complex biological molecules (usually from dead organisms) into simple molecules; these simple molecules can then be used as materials by living organisms to build more cells

Aerobe

organism that uses O2

Anaerobe

organism that does not use O2

Facultative

organism can use the ability if necessary

Obligatory

must use only this ability

Autotroph

organism that obtains its carbon from O2

Heterotroph

organism that obtains its carbon from organic molecules that were synthesized by other organisms

Cells need these in order to survive, grow, and reproduce

-energy source: radiation that is captured by electrons in pigment molecules; electrons that already carry energy that are part of ions or molecules
-matter source: ions, water, sources of the six major elements

T/F ALL cells get energy and matter to live from the environment

True

What is a cell made of?

70% of water
15% proteins
6% RNA
4% small ions/molecules
2% phospholipids, polysaccharides
1% DNA

Cells get biological molecules by

building them from small biological molecules

Why is it easy for cells to find small biological molecules?

most small biological molecules are already part of other larger macromolecules

Most concentrated environmental sources of biological macromolecules

other living systems, products of other living systems, formerly living systems

Digestion

use of an enzyme to hydrolyze larger molecules into smaller molecules that can be used by a cell

Digestive enzymes (4)

-proteases digest proteins
-nucleases digest nucleic acids
-carbohydrases digest mono-, oligo, and polysaccharides
-lipases digest lipids

How do digestive enzymes serve the survival of a cell?

-gene that holds info. for building a digestive enzyme is transcribed into mRNA
-ribosomes translate: information in mRNA is used to construct molecules of digestive enzyme
-digestive enzymes are transported to plasma membrane, and then exported from the cell
-digestive enzymes break covalent bonds of any nearby biological macromolecules, releasing small molecules
-transporter proteins in the plasma membrane import small biological molecules into the cytoplasm
-other enzymes in the cytoplasm use small biological molecules to build new biological macromolecules for the cell

Microbiota

-microorganisms that live on or in a multicellular organism
-EVERY multicellular organism (people, animals, plants, and fungi) has microbiota
-NO multicellular organism can live for very long without its microbiota

Why can't people survive off only eating plants?

-people cannot digest cellulose; in order to digest cellulose an organism must be able to synthesize the digestive enzyme cellulase

Animals that survive off plants

CANNOT synthesize cellulase however their gut microbiota can synthesize cellulase to digest cellulose

Cellulose

polysaccharide that makes up plant-cell walls

How many recognized Bacterial phyla?

40

How many recognized Archaean phyla?

20

Archaea located

-many have been characterized in the human digestive tract and on skin
-other locations have not been studied yet

Predominant archaeal taxon in human microbiome

Methanobrevibacter sp.