MCAT BIOLOGY

what makes a cell-CELL

1.cell is the basic unit of life of an organism

2.it carries genetic material in the form of DNA

3.it arises from pre exisiting cells

4.all living organisms are made of cells

how is subcellular things studied today

autoradiography,microscopy and centrifugation

compound light microscope

1.diaphragm—controls the amount of light entering

2.course or fine adjustment knob—-controls the focus

phase contrast microscope

tradeoff os seeing living organism but almsot no contrast or focus at specific organs

most visually focused microsocope

electron microscope—but leads to death of an organism inorder to examine them

uses heavy metals like OsO4

light and electron microscope difference

ranges in nanometers(wavelength of lights) and picketers(beam of electrons)

electron microscope’s biggest achievement

differentiate between outer and inner mitochondrial membranes

autoradigraphy

use of x rays and radio frequency rays

based on how biochemical reactions occur with the different component of the body and when put in dark shows areas where a reaction occurs to create a better x ray image

centrifugation

works on density and shape difference and how greater force shows greater effect on the greater density and thus pulling it down more

more dense-ribosomes and

less dense —mitochondria and lysosomes

prokarya

contains a bacterial genome insde a nucleoid region but also had small pieces of DNA called plasmid

plasmids are beneficial because

helps differentiate a bacterial strain that is suspectible to an antibiotic and one that is resistance to it

plasmids can reproduce and carry multiple plasmids to next generation for carrying on the antibiotic resistance

spherical and rod shaped bacterias are

staphylococcus aureus and escherichia coli

we always look for features found specifically in

a specific bacteria in that drug to kill it like arithromycin for ear infection kills a specific bacterial ribosome smaller than the eukarya ribosome

largest to smallest proteins making up the cytoskeleton

Microtiubules >intermediate > actin

phospholipid bilayer has

protein and lipid rafts

hydrophobic tail but a hydrophilic head

major component of hydrophobic tail

cholesterol—helps maintian the membrane fludiity and stiffness and produces steroid hormones in animals

more non polar means

more easier to transverse in the hydrophobic nature of the core

two imp. proteins

transport

CAMs(cell adhesion Molecules)—helps with cell development and differentiation

nucleus is

helps direct protein synthesis and carries genetic blueprint during cell replication

nucleolus helps with

sysnthesis of rRNA

ribosomes gives out the products to

endoplasmic reticulum

rough and smooth endoplasmic reitculum

production and sorting of protein products while smooth helps with detoxification of drugs or synthesis of lipid

golgi helpsw ith

repackaging material recieved from the smooth ER and further direct them to cell surface

where they travel by secratory vesicles (process of exocytosis)

vesicles are helping with

wrapping and sending out materials (trasport ) and store things that are processed,secreted or digested

lysosomes help with

recycling material ,it kind of acts as a garbage dump so sequester the hydrolytic enzymes(Endosomes) to not damage the cell—kind of digests them and also can cause autolysis (cell death)

mitochondria

-outer -contains material for respiration

-inner -contains material for ETC (enzymes and molecules)

cristae function ?

increases surface area for all the enzymes to sit in

which organelle is passed only from mother

MITOCHONDRIA

apoptosis linked with mitochondria how?

certains enzymes might be releases int eh etc (which are not supposed to) during apoptosis

Mitochondria are

semiautonomous

chloroplasts

have their own dna and may ahve evovled by symbiosis (like mitochondria)

peroxisomes and glycoxisomes

present in animal and helps catalyze the detoxification in liver and converting food to fuel

glycoxisomes are in plants and they also help break down food to usable forms

cell wall type in plants and fungi

cellulose and chitin

centrioles

present only in animals and help in spindle formation

also responsible for the highway system like microtubules

cytoskeleton contains:

intermediate,microtubules and microfilamnets

microfilament

made of actin ,is solid and forms smallest road during muscle contraction

in muscle onctraction—-actin meets myosin

helps with movement of materials

microtubules

forms the largest roads ,are hollow and made of tubulin

helps with seperation of chromosome in division

cilia and flagella movement to trap foreign particles

intermediates help with

maintaining overall integrity of cytoskeleton and made of fibres

osmosis

movement of water fro a lower solute conc to higher solute conc and thru the semi permeable membrane which stops the solute from moving

active transport requires

energy in the form of ATP

faciliatted diffusion (passive transport)

for large,charged or polar molecules

so integral membrane proteins help faciliate the movement

endo and exocytosis

creates environments for a specific process like

endocytosis:

ingestion of material (which is kept away from cytosol because could be toxic) into cell by cellular membrane —-

pinocytosis -ingestion of fluid and small particles

phagocytosis-for larger particles

exocytosis

oppsoite of endocytosis

like in nervous system or intracellualr signalling

movement for what type of molecules

active

facilitated

osmosis

diffusion

polar charged

large,polar and charged

water

small and non polar

epithelial tissue

helps with protection from invasion or dessication

also helps with secretion,absorption or even sensation

connective tissue

provides framework like in tendons,adipose tissue ,cartilage

nervous tissue

helps with coordinated contorl,signalling using electrochemical gradient

virus

-acellular

-OBLIGATE INTRACELLULAR PARASITES—do not replicate on their own

-hijacks a cell machinery and starts producing virions

-protien coating is called capsid

what are bacteriophage

a type of virus that attacks bacterial cells

doesnt enter entirely but sends out genetic material inside for replication

diseases caused by virus are

mumps, measles,chicken pox,influenza,hepatitis ,AIDS

why is ti more difficult to treat a viral disease than a bacterial one

virus doesnt have its own organelles and lives inside host cells —so difficult to comabt eh viral replication and destroy htem using vaccination

wernicke kershakoff syndrome

balance problem,delirium and excessive alcohol consumption leading to difficulty in forming memories

characterstics of enzymes (proteins)

lowers activation energy,doesnt change equilibrium constant , increases rate of rxn, doesnt change H or G , aren’t consumed or changed in a reaction and are specific for a specific chemical(substrate)

lock and key theory

an active site of the enzyme having a specific shape for the Key(substrate -specific) to attach itself to

induced fit theory

-more scientifically proven

-based on conformational shifts made when enzymes and substrate meet at active site

and after the release —both come back to normal shape and state (shift )

-releases and absorbs energy during these conformational shifts

thiamin ?

a cofactor for enzymes that control metabolism or nerve conduction and its deficincy leads to the wernicke syndrome

cofactors are

nonprotein molecules that make enzymes efficient

types of cofactors

1.organic (co enzyme)

2.Metal ion

human cofactor name

biotin

holoenzyme and aponenzyme

enzyme with cofactor and enzyme without cofactor

factors affecting enzyme kinteics

pH, temperature,conc. of substrate / enzyme

Km is directly proptoriomnal to

affinity for the susbtrate

½ V max is

Km= S

effect of temperature

works best when risen to optimal (37 degree) and after that it becomes denatured

pepsin

works best at 2 pH

pancreatic enzymes near small intestine work at

8.5 pH

7.3 in human blood is still considered as

ACIDOSIS

allosteric effects

allosteric sites—sites other than active sites

enzymes are of two types here:

allosteric inhibitors or activators

-activators will increase the binding power of the active site for the substrate whereas inhibitor will lessen it

-other than that,affinity of an enzyme for a substrate is also affected by this

hemoglobin binded to one oxygen unit

increases affinity to bind to the other subunits of oxygen

inhibition has 3 types:

non competitive,uncompetitive and competitive

competitive inhibiton

-occupies the active site and can be removed by

addng more substrate or increasing th substrate: inhibitor ratio

noncompetitive inhibition

occupy other binding sites but not the active one (Allosteric site)

-cannot be removed by adding more substrate

-reduced the Vmax but the Km remains constant

what does non competitive mean here

the allosteric and the active sites are not competing for the same spot, and so no competition lies here

example of irreversible inhibition

aspirin (acetylsalicylic acid)—-actelyases cyclooxygenase and prevents pain

thus cyclooxygenase needs to be synthesized more using tracritpion and translation to produce prostaglandins

what does feedback inhibition effect do in general

the product is too much so it just binds to the enzyme to not be able to bind to substrate to produce more product

example of why tight control of an enzyme is required

trypsing (digestive enzyme) will digest the organ itself if not controlled

what are used to control the enzyme rates

zygomens(inactive forms of enzymes ) like trypsinogen for trypsin

zygomens have

-regulatory domain(needs to be removed before use)

-catalytic domain

what works the same as zygomens ?

apoptic enzymes

how does a person suffering from methanol poisioning treated ?

providing intravenous ethanol which works like an inactive form of the methanol

coenzyme Q10 effects

-antioxidant

-immune functions

-biochemical fucntions

-implicable in parkinson and alzeihmer

-anti aging fighting against the free radical chemicals

where is Q10 found

-inner mitochondirla membrane and helps produce ATP

plants and human ?

anabolic and catabolic (we break down organic moelcules produced by plants)

glucose configuartion is also called

pyranose (a ring structure)

photosynthesis characterstics

-endothermic

-plants are anabolic in nature

-C-O in CO2 and O-H in H2O is broken down and then rearranged to form the main mediator called glucose

ATP

made of adenine nitorgen base, ribose sugar and 3 phosphate groups

ribose and deoxyribose difference

2’C — 2’OH (ribose)

2’C——2’H (deoxy)

where is energy stored in atp and why is it called high energy ?

-high energy because 3 phoshpate groups mean too many negative charges in closer proximity to one another

-stored in 3 phoshpate bonds

ATP can be broken down to:

ADP+ inorganic phosphate

AMP + pyrophosphate

hydride ions are good?

reducing agents like LiAlH4 or NaBH4

how much energy always releases

approx 7Kcal/mol

most energy needed for muscle contraction or actvie transport is by

ATP breakdown or glucose catabolism

coenzymes are

NAD+ and FAD

coenzymes do what role?

accept high energy electrons

high energy electrons are in the form of

Hydride ions —whihc do not give away their energy but are transported

these electrons are transported to what ?

to an electron acceptor (oxygen) which couples to give ATP production

what does High energy electron do?

travels through thr ETC in inner mitochondrial matrix to be able to convert to ATp again for use

what happens to NAD+ and FAD in glycolysis and Krebs?

reduces to NADH and FADH2 (after receing electrons in the form of Hydride)

glyoclysis in short term is

breaking own gluocse to two smaller organic molecules and occurs in the cytoplasm