(2) BIOCHEM: Biomolecules, Biochemical Systems, Cell

molecules

- building blocks of cells

biomolecules

- chemicals or molecules present in the living organisms

- compounds of carbon

cellular pool

- the sum total of different types of biomolecules, compounds and ions present in a cell

water

- constitutes 50-95% of cells content by weight

10,000

- the number of kinds of molecules present in animal and plant cells

carbohydrates, lipids, proteins, nucleic acids

- organic biomolecules

water, mineral salts, gasses

- inorganic biomolecules

nucleotides

- level 1

- monomeric unit of chromosome

DNA

- level 2

- macromolecules of chromosome

amino acids

- level 1

- monomeric unit of plasma membrane

protein

- level 2

- macromolecules of plasma membrane

sugars

- level 1

- monomeric unit of cell wall

cellulose

- level 2

- macromolecules of cell wall

chromosome, plasma membrane, cell wall

- level 3

- supramolecular complexes of the cell and its organelles

carbon

- most versatile and the most predominant element of life

macromolecules

- large sized, high molecular weight

- above 10,000 daltons

- found in the acid insoluble pool

- ex. carbohydrates, lipids, proteins, nucleic acids

micromolecules

- small sized, low molecular weight

- between 18 to 800 daltons

- found in the acid soluble pool

- ex. minerals, gases, water

carbohydrates

- monosaccharides joined by glycosidic bond

- ex. starch, cellulose

- elements: C,H,O

- functions: energy source structural component, reserve food

protein

- amino acids joined by peptide bond

- ex. insulin, collagen

- elements: C,H,O,N,S

- functions: enzyme, structure movement, defense hormones

nucleic acids

- nucleotides joined by phosphodiester bond

- ex. DNA, RNA

- elements: C,H,O,N,P

- functions: stores genetic information

lipids

- fatty acids and glycerol joined by ester bond

- ex. fats, oils, waxes

- elements: C,H,O

- functions: energy source, insulation, membrane components, hormone

cell

- basic, structural and functional unit of life or living organism

- discovered by Robert Hooke

- often called the building block of life

unicellular

- consist of a single cell

- ex. bacteria

prokaryotes and eukaryotes

types of cells

prokaryotes

- pro meaning "before"; karyon meaning "nucleus"

- lack a well defined nucleus and possess relatively simple structure

- includes various bacteria

eukaryotes

- eu meaning "true"; karyon meaning "nucleus"

- possess a well defined nucleus and are more complex in their structure and function

- higher organisms (animals and plants) are examples

ribosomes, cell membrane, DNA, cytoplasm

similarities of prokaryotic and eukaryotic cells

prokaryotic

- no membrane bound organelles

- no true nucleus

- unicellular

- 0.1-5 micrometers

- has cell wall

- asexual reproduction

eukaryotic

- contains membrane bound organelles

- contains true nucleus

- uni-, multicellular

- 10-100 micrometers

- asexual and sexual reproduction

prokaryotes

- flagella consists of two protien building blocks

eukaryotes

- flagella is complex

- consist of multiple microtubules

prokaryotes

- glycocalyx is present as a capsule or slime layer

eukaryotes

- glycocalyx is present in some cells that lack a cell wall

prokaryotes

- cell wall is usually present

- chemically complex (typical bacterial cell wall includes peptidoglycan)

- cell wall is chemically simple when present

prokaryotes

- plasma membrane has no carbohydrates and generally lacks sterols

eukaryotes

- plasma membrane has sterols and carbohydrates that serve as receptors

prokaryotes

- no cytoskeleton or cytoplasmic streaming in the cytoplasm

eukaryotes

- cytoplasm has cytoskeleton and cytoplasmic streaming

prokaryotes

- DNA arrangement is single circular chromosome, lacks histones

eukaryotes

- DNA arrangement has multiple linear chromosomes with histones

prokaryotes

- cell division is binary fission

eukaryotes

- cell division is mitosis

prokaryotes

- sexual reproduction is transfer of DNA fragments only (conjugation)

- no meiosis

sexual reproduction

• reproduction involves meiosis

nucleus

- spherical and largest part of the cell

- contains nuclear membrane, nucleoplasm, nucleoli, and genetic material DNA

- controls cellular activities

- contains DNA, RNA, and proteins

nuclear membrane

- this part of the nucleus is continuous with endoplasmic reticulum

RNA

- helps in protein synthesis

DNA

- helps in production of chromosomes

DNA polymerase

- marker enzyme

- site of DNA to RNA synthesis

endoplasmic reticulum

- a network of membrane continuous with nuclear membrane

- provides surface area for number of chemical reactions

- helps in the synthesis of steroids, proteins, etc

- provides a pathway for transporting various chemical substances

- helps to concentrate the products of synthetic activities of cell

ribosomes

- tiny granules present in cytoplasm as well as on surface of endoplasmic reticulum

- contains special type of RNA called r-RNA

- main site for protein synthesis

lysosome

- membranous vesicles which contains powerful digestive enzymes which are capable of breaking down many kinds of molecules

- helps for intracellular digestion

- autolysis

- phagocytosis

golgi apparatus

- consists of 4-8 flattened bag like channels stacked upon each other

- located near the nucleus

- helps in intracellular sorting of proteins

- helps in packaging of secretory products

mitochondria

- small intracellular organelles and are known as power house of cells

- bounded by inner folded and outer smooth membrane

- inner surface have many cristae and are covered with F1 particles

- the main site for synthesis and storage of ATP

- the site for citric acid cycle, B-oxidation, urea cycle, ETS

- contains special DNA and is self-replicative

- performs the main function of conversion and transfer of cellular energy

cell/plasma membrane

- surrounds the cell and separate it from other cells and external environment

- composed of proteins, phospholipids, carbohydrates, minerals, etc

- involves in transport of molecules in and out of the cells

- gives shape to the cell and covers and protects the cell and organelles

- helps in intracellular adhesion and communication

- forms channels of ER

- can act as a physiological sieve

- semi-permeable barrier

- dynamic in nature

Singer and Nicolson

proposed the lipid bilayer model (fluid-mosaic model)

passive transport

- movement down the concentration gradient

- expenditure of energy not required

- ex. simple diffusion, osmosis, facilitated diffusion

active transport

- movement against the concentration gradient

- energy (ATP) expenditure by cell

- requires carrier protein

simple diffusion

- movement through phospholipid bilayer

- from high concentration to low concentration without a protein

osmosis

- requires semi-permeable membrane

facilitated diffusion

- requires carrier protein or pore protein (channel protein) to move particles from high to low concentration using a protein

hypotonic solution

- lower concentration

- water move into the cell

- cell expand and lyse

isotonic solution

- equal concentration

- overall concentration are equal

- cell remain constant

hypertonic

- higher concentration

- water move out from cell causing crenation

plant cell

- has cell wall (rigid shape)

- large central vacuole

- has chloroplasts (autotroph)

- lack centrosomes and lysosomes

animal cell

- has no cell wall (irregular shape)

- numerous small vacuoles

- no chloroplasts (heterotroph)

- has centrioles/centrosome and lysosome

ATP (adenosine triphosphate)

- the energy required for muscle contraction

- the "energy currency" in the cell

- provides energy for these cellular processes: making proteins, energy for photosynthesis, active transport

- used for the synthesis of genetic materials, and macromolecules and cellular components,

- used muscle movement, transportation of molecules, and electrical energy

ATP-CP, anaerobic glycolytic or lactic acid system, aerobic sustem

three main biochemical systems

ATP-CP/ ATP-PCr/ phosphagen system

- this system of energy provision is used for sudden bursts of energy but cannot be sustained for more than about 6-10 seconds

- one-step chemical reaction

- anaerobic reaction

- ratio of energy produced is 1:1

phosphocreatine

- sometimes referred to as phosphocreatine (PCr)

- a substance which is stored within the muscle cells but in relatively low amounts

- once the store is depleted, it takes time for the stores to be restored

creatine kinase (CK)

- the enzyme that catalyzes this reaction: CP is broken down into creatine and inorganic phosphate (Pi)

- Pi is transferred to an ADP to rephosphorylate the ADP to ATP

glycogen

- this is glucose but normally found in the muscles as this

anaerobic glycolytic or lactic acid system

- the process of the breaking down of glucose to provide chemical energy

anaerobic system

- this break down of glucose provides the body with explosive short term energy without the need for oxygen

- the ATP it produces powers the working muscle cells when the blood is unable to provide them with oxygen quickly enough

- sprinters are powered by this system (enables them to blast out of the blocks and get to their top speed in about 7 to 10 secs)

lactate

- helps performance during intense exercise

- glucose is converted to this in the absence of oxygen (glucose to pyruvate to ____)

krebs cycle

- provide ATP on a virtually limitless basis as long as fuel (carbs, fats, or proteins) and oxygen are available

- primary purpose is to generate high energy molecules such as ATP, NADH, and FADH2

aerobic metabolism

- the collective term of krebs cycle and electron transport chain (ETC)

citric acid cycle or tricarboxylic acid cycle

- oxidation of acetyl CoA to carbon dioxide and water

- occurs in the mitochondrial matrix, in close proximity to the ETC