Exam #1 for IB Bio SL

cells are a __ for life

fundamental unit / building block

who used microscopes and observed cells as basic parts of all organisms creating the cell theory?

Robert Hooke

at 7400x, light microscopes become ineffective due to what?

due to the physical limits of light (wave length of light too large)

what is "resolution"

The ability to clearly distinguish the individual parts of an object

electron microscopes' caveats

no color, kills cells, only observe dead cells - while light microscopes can see color and live organisms

fluorescent stains

stains used on colorless cells for easier viewing

Immunoflourescence

fluorescent markers [antibodies] that attach to specific antigens showing where specific chemicals or proteins are located.

freeze fracture electron microscopy

- used to produce surface images

- rapidly freezes at -190c propane then cut with a blade

- ice formed are vaporized to enhance texture of surface [etching]

- vapour of platinum or carbon fired onto fractured surface to create replica

- replica examined with electron m. and usually fractured at middle of membrane [weakest point]

cryogenic electron microscopy

aka cryo em

- pure protein solution applied to a grid then flash frozen instantly using liquid ethane

- multiple patterns and images of the many proteins combined to form one 3d image of proteins

- advantage: instantaneous - allows to view protein at the instant time

plasma membrane + functions

outer boundary enclosing all of cells contents

- functions: controls entry and exit of substances

- pumps substances in the cell despite low conc. outside the cell

- good at preventing entry of toxic substances

- maintains concentrations different than those outside [homeostasis]

- permeability depends on lipid structure

lysis and autolysis

membrane bursts and cell dies. Autolysis is self causing. Can happen due to excess pressure or viruses.

cytoplasm and function

functions:

- dissolved substances suspended in water

- enzymes in the cytoplasm catalyze reactions

- metabolism provides cells with energy to repair and produce proteins

DNA

carry out functions and instructions to make protein for structure and for enzymes

- can be copied and passed on by daughter cells that are heritable

-stored in nucleus; in bacteria they are stored in cytoplasm in nucleoid region

Prokaryote [prok] dont usually have ___ that contains chromosomes

a nucleus

what are the 3 main eukaryotes

plants, animals, fungi

prokaryote properties

- first to evolve and simplest

- has cell wall sometimes [thicker and stronger to support strength and prevent bursting] contains peptidoglycan

- no nucleus

- dont have cytoplasmic organelles besides smaller 70s ribosomes.

- DNA in cytoplasm is naked and forms a loop

eukaryotes properties:

- compartmentalized organelles

has nucleus with chromosomes and DNA [helix]

- 80s larger ribosomes

- dna attached to histone proteins

- has mitochondria in cytoplasm with double membrane that is folded to increase surface area and carries out aerobic respiration for ATP

living organisms have what 7 properties

homeostasis to maintain internal environment

metabolism for biochemical reactions

nutrition for energy growth and repair

excretion for removing waste

growth to increase cells or size

response to stimuli

and reproduction sexually or asexually

main differences among eukaryotes [should know this]

plastids - only in plants and stores food [chloroplasts]

cell wall - in fungi [chitin] and in plants [cellulose]

vacuole - small in animal, large to control pressure and store stuff in fungi and plants

centrioles - animal cells: spindle for mitosis. absent in fungi and plants except in male gametes

undulipodia [cilia, flagella] in many cells and male gametes of animal cells. IN fungi and plants: absent in most except male gametes

4 main examples of atypical cell structure in EUK

red blood cell, phloem tube elements, skeletal muscle, aseptate fungal hypae

red blood cells atypical structure is for what?

Is for maximizing oxygen transportation.

as they mature nucleus is pinched off and destroyed by phagocytes. To be smaller and more flexible

- no nucleus and mitochondria so RBC cant repair so only 100-120 day lifespan

phloem tube elements are atypical in what way

in xylem vessels, all walls between cells removed and cell contents break down creating hollow tube for water to flow

- in phloem, sieve tube vessels has large pores and nucleus breaks down. But plasma remains for transport

- adjacent companion cells with nucleus helps sieve tube elements survive by providing it proteins.

in skeletal muscle, why is there hundreds of nuclei per cell.

cells fuse forming long muscle fiber that can be many inches long. The entire cell shares hundreds of nuclei allowing for greater recovery during cell damage.

aseptate fungal hypae

large structure of cells with shared nuclei

essential idea of cells:

the evolution of multicellular organisms allowed cell specialization and cell replacement

unicellular organisms are

singled celled and can carry out all of the functions of life independently

multicellular organisms have

specialized cells to carry out specific functions

1. cell theory's basic principles

A. All living things are made of cells

- except viruses

B. cells are smallest unit of life

- cell components cannot survive alone

- organelles carry out various metabolic functions

c. cells only formed by division of pre existing cell

- by mitosis and meiosis in euk.

- binary fission in prok.

- all cells descend from simpler common ancestors

2. All living organisms carry out the functions of life..What are the functions?

nutrition, growth, reproduction, response to stimuli, excretion, homeostasis, metabolism

- unicellular organisms such as amoebae are capable of all these functions

- while multicellular organisms have specialized cells to carry out specific functions.

Robert hooke

first to observe "small chambers" in cork and call them cells [inspired by monastery cells]

Leewenhoek

The first scientist to describe living cells as seen through a simple microscope

Spontaneous generation debunked by?

Pasteur's test. 2 broths in a container with curved neck, the other container with no curved neck. The one with curved neck had microorganisms meaning the bacteria came from outside in the air

A. electron microscopes

TEM transmission electron microscopy

- much higher resolution since they use beams of electron

- give higher magnifications to see smaller structures

- helped scientists see ultrastructure of cells

B. fluorescent stains and immunofluorescence

- fluorescence is absorbance of light and reemission at longer wavelength

- usually use intense single wavelength light sources like leds or lasers

- light re emited by a stained sample

- immunoflu. is when antibodies bind to specific chemical in cell are produced. A fluorescent marker is linked to the antibodies

- multicolored images can be made using multiple types of antibodies

freeze fracture EM

used to produce images of surfaces of cells

- sample plunged into liquid propane

- steel blade fractures sample through weakest point

- vapor of plat or carbon fired onto surface to create a coating

cryoem

reveals protein structures

- thin layer of protein solution flash frozen with ethane to create glass like to prevent ice formation

- the grid is placed in a electron microscope and detectors record patterns of electrons transmitted by individual protein molecules

- computer uses multiple images to give 3d image

- resolution of 0.12 allows individual atoms in protein to be located

ultrastructure is what?

cell structures revealed by electron microscopy [light microscopy limited to seeing only nucleus, cell walls, etc,.]

prokaryotes are pro because?

pro = before. So theyare smaller and came first in terms of evolution

Parts of prokaryotes. Know all.

cell wall = protecting protein based coating

plasma membrane = selectively permeable

pili - attack to other bacteria from dna trasnfer

cytoplasm = contains emzymes for metobolic reactions

nucleoid = closed loops of bacterial dna in condensed area [no nucleus]

70s ribosomes that are smaller = for protein synthesis

flagella for movement

mesosomes

Thought to be in folds of plasma membrane but turned out to be electron microscope artifacts [not real]

b. prokaryotes reproduce by binary fission

binary fission = two splitting

1. much simpler method of reproduction compared to euk

2. much faster growth that is exponential

eukaryotes in 3 words

membrane bound organelles

eukaryotes have a __ cell structure

compartmentalized.

have true nucleus. membrane bound organelles.

main functions of organelles of EUK

plasma membrane = controls entry and exit of cell waste

mitochrondia for converting sugar to atp

free ribosomes - produce proteins

nucleus = membrane bound nucleus contains DNA. Nucleolus is area of densly packed DNA

rough er = ribosomes on rough er produce proteins

golgi apparatus - modifies and packaged proteins produced in rer to be exported by cell via exocytosis

cytoplasm = contains enzymes and solutes needed for metabolic rxns in the cell.

nucleolus:

Found inside the nucleus and produces ribosomes. Has densly packed DNA

lysosomes

contains digestive enzymes for breaking down nutrient molecules and dead cell parts for recycling

how does membrane play a role in lysosomes

the environment inside lysosomes would eat up the rest of the cell. Membrane allows mutiple varying environments to exist in the cell

types of vesicle transport

endocytosis and exocytosis

exocytosis used for lysosomes and golgi apparatus

- protein or waste enters vesicle that fuses with cell and releases

what structures are found in plant cells but not in animal cells, and vice versa

in plant cells: cell wall, chloroplasts, vacuole

in animal cells - lysosomes

extracellular components of cell

plasma membrane, plant cell wall.

turgid vs flaccid cell

turgid has high turgor pressure supported by vacuole. Flaccid cell wilts.

atypical cells in euk include what 4

red blood cell, skeletal muscle, aseptate fungi, phloem sieve tube elements

red blood cells' atypical-ness

1. do not have nucleus for more space for hemoglobin [hemo group carries o2]

2. without source of proteins for repair and other functions, rbc live 4 month at most

3. no nucleus and mitochondria or ribosomes\

skeletal muscle's atypicalness :

1. fiber enclosed in plasma membrane that is 300 mm long [1 feet] and contains hundreds of nuclei shared

2. many nuclei within 1 fiber

3. straited appearance due to regular arrays of protein filaments

4. shared nuclei allow for faster healing

phloem sieve tube elemnts

1. tubes that transport sap in plants

2. have nucleus but it breaks down so sap flows more easily

3. supplied with proteins by adjacent companion cells that have nucleus and rer

aseptate fungi

Type of fungi with hyphae that is not partitioned by septa; multinucleated

- long undivided chains of hyphae with many nuclei

what makes an organelle.

1. euk cells have variety of cells to perform according to its adapted structure to perform specific functions

2. have a specific function and is descrete

what cell structures are not organelles n why

cell wall - outside membrane [extracellular]

cytoplasm - diverse functions

cytoskeleton - not discrete in structure

seperation of nucleus and cytoplasm's via membrane

a. euk modify mnra before translating into polypeptides[proteins

b. this happens inside nucleus where rna is produced by transcription

c. nuclera membrane ensures that the post trasncriptional modification is finished before mRNA meets ribosomes

thats why prok have more mutations since they dont have this mRNA modification since they lack a membrane bound nucleoid region. ribisomes translate mrna as soon as it is produced

advantages of compartmentalization:

1. small volume allows enzymes and substrates to be concentrated which speeds up enzyme activity

2. ph level kept ideal at one part of the cell ideal to organelles function

3. incompatible biochemcial processes can be kept seperate. eg, digestive enzymes stored in lysosomes to not eat up the cell.

what is small in animal cells and large in fungi and plant cells

vacuoles

what do plants only have that animal and fungi cells dont

plastids [chloroplasts]

what do animals have that fungi and plant cells dont

centrioles for mitosis. And have cilia more often.

plastids

double membrane organelles like chloroplasts and amyoplasts to store starch

animal and fungi cells lack plastids

centrioles

composed of microtubes and used during mitosis and meiosis to assemble spindle

vacuoles

sacks of fluid in cytoplasm. Large in cells and fungi to store substances and pressurize the cell. Some animal cells have them to expel excess water and digest food and pathogens.

cilia and flagella

whiplke structure to move. Only in animal cells.

Some plant cells have male gametes with flagellum

This flash card concludes TOPIC A2.2.1-2.9. Everything after this flashcard is B2.1.1 - B2.1.8

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what is plasma membrane and its function

forms a border between cell and environment. Bilayer of phospholipids form continous sheet that controls passage of substances

phospholipid molcules have what kind of heads. And 2 of what kind of tails?

have 2 phosphate heads and 2 hydrocarbon tails

describe the phosphate heads and hydrocarbon tails' relationship with water

tails are hydrophobic and heads are hydrophilic. So membrane core has low permeable to hydrophilic particles, such as ions with charges and polar molecules

hydrocarbon chains tails dont repel hydrophobic solutions, so why are they considered hydrophobic

they are simply more attracted to each other and solutes, than the water outside

what 2 main factors affect membrane permeability

molecule size and charge

what is the solution outside the cell c alled

aqueous

what makes diffusion a passive process

it requires no cell energy, its a natural process and characteristic of substances, even outside the cell

simply, its the spreading out of particles in liquids and gases because of random continous motion of particles. More particles move from area of high conc. to lower conc, than the opposite direction, thus the net movement is from high to low- down a concentration gradient

simple diffusion only happens to particles ___ with phospholipid bilayer

permeable. Nonpolar particles like o2 can diffuse easily

Why cant ions defuse easily

center of membrane is hydrophobic which repel chargesq

integral protiens

hydrophobic on a part of their surface so they embed into the hydrocarbon chain in the center

may fit in 1 phospholayer or sit across both. Hydrophilic parts project through regions with phosphoheads

pheripheral proteins are

hydrophilic and do not embed into the membrane

attach to surface of integral protiens

some have single hydrocarbon chain to anchor itself to membrane

how does protein content depend on function of membrane

more active membrane has more protiens. Membranes in nylon shealth are 18% protien. While in mitochrondrion, they ahve 75% protien content

what is the simple diffusion of only water molecules across membranes

osmosis

how is osmosis different than diffusion

requires membrane

osmosis is due to what

the difference in concentratoin of substgances dissolved in water

water follows __

solute. H2o moves from regions of high solute conc to regions of low solute conc.

aquaporin

protein to allow for quick water passage. It narrows to the point the width is slightly wider than h2o width, allowing for single file.

positive charges at this point prevent h+ protons from passing

synonyms of semipermeable

partially permeable, semi, selective permeability

facilitated diffusion and active transport are different from simple diffusion how?

they require specific proteins specific to certain particles.

they are seletively permeable

glycoprotein

protein with glyco carbohydrate attached to it

part of the membrane with protien embeded, with carb part projecting into outside the cell

gylcolipids

lipids attached to carbs. Carb part is 2-4 sugar units and is short. Lipid part fits into hydrophobic core

Glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication

glycoprotiens and glycolipids form a carb rich alyer of outerface of plasma membrane with aqueous solution in gaps between carbs

this layer is called glycocalyx and help adjacent cells fuse

roles of glycoprotiens and glycolipids

glycolipids help in cell recognition and in immune system to distuingush between self and nonself cells so pathogins can be destroyed

fluid mosaic model

bilayer of phospholipids w proteins in variety of fluid positoins

pheripheral protiens attached to inner outer surfaces, with integral proteins potruding in 1 or both sides

proteins are linked to tiles in mosaic, phospholipiods freely move LATERALLY in bilayer, and so do proteins

protein channels

proteins in membrane to help molecules that are ion or polar or too big to pass through phospolipid

protein connects aqueous solutoin with cytoplasm

how are protein channels for facilitated diffusion seletive

they are selective because only 1 specific particle / molecule can pass thru, how?

diameter of pore and chemical properties ensures only 1 type of particle pass throughs protein channels

net movement

in diffusion, particles will go from 1 side to the other and vice versa. But if it goes from inside to outside more than outside to inside, it could be said that the NET movement is from inside to outside

facilitated diffusion requires no

energy. No cellular energy like atp.

different from simple diffusion, in which particles move across membrane without protein channel

pump proteins are active transport, how?

because they are active, so use energy in the form of ATP

pump protein characteristics

only from 1 side to the other, 1 direction

- allows for pumping against high concentration /against concentration gradient

- have 2 conformations. 1 original conformation in which particle enters, and 2nd conformation in which the particle passes out. ATP is used to go from stable 1st conformation to 2nd, but ATP is not needed for the reverse conformation.

main function and purpose of pump protien

- specific particles to be pumped

- allows cells to control content of cytoplasm precisely, even allowing specific solutes to be aborbed even if they are in low concentration outside the cell [against concentration gradient]

production of unspecialized cells starts after what?

fertilization. Fusion of male and female gamete to produce a single cell.

- in multiceullar organisms, cells divided by mitosis repreadly to generate embryo of identical cells