Section C Flashcards
Cell membrane
it is a semi-permiable organelle ,which allows material in and out of the cell
heads” pointing outward from the membrane
Hydrophobic “tails” pointing inward from the membrane
Also, consists of proteins and carbohydrates
(peripheral) and integral (embedded) proteins
Receptors
Channels
Carriers
Cholesterol molecules stabilize the membrane and provide a decrease in fluidity at low temp
Cell markers account for blood type
Glycoproteins and glycolipids attached to outer surface
Flagella
they are whip like hairs/tails
helps in the motility of the bacterium
Pili/Fimbriae:
are small hair like projections on the surface, allow bacteria to stick to the surface and also used to move DNA plasmids between bacteria
Plasmid :
DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA.
They are double-stranded and, in many cases, circular. Plasmids usually occur naturally in bacteria.
Plasmids are responsible for the antibiotic
resistance .
Zygote
fertilized egg
Union of a sperm and an ovum
From the zygote other cells will be produced that have specific structures and functions
Differentiation
process of cells becoming specialized
Mature cells are usually more specialized or differentiated than immature cells
Nucleus
Large, spherical organelle that has a double membrane with holes or pores
Stores genetic information which directs all cell activities
Nuclear envelope separates nucleus from cytoplasm
Deoxyribonucleic acid (DNA)-
in the nucleus
blueprint to new cell creation
Deoxyribose C5H10O4
A pentose sugar like ribose or deoxyribose, a phosphate or polyphosphate group and a nitrogen containing base
Has a spine ( backbone) of alternating (repeating) deoxyribose (sugar) and phosphate molecule covalently bonded in a long chain
The 2 chains are held together by hydrogen bonds between the bases
Adenine is always bonded to Thymine and Cytosine bonded to Guanine
Joined by hydrogen bonds
DNA polynucleotide chains pair up with one another (primary structure)
Bond together in twisted double strand (double helix)
Double-helix wraps around some proteins (tertiary structure)
separate at the nucleotide base for replication
Nucleolus
in the nucleus
Chromatin- coils to chromosomes before the cell divide
Histones
holds chromosomes together
Nucleoli -
Contains rRNA
Site where ribosomes are formed
Ribosomes are small bodies in the cytoplasm containing RNA and protein
Cytoplasm
Between the cell membrane and nucleus
Cytosol
Liquid portion
Made up of water, proteins, ions, and nutrients
Mitochondria
Responsible for producing cell energy, in the form of molecules called adenosine triphosphate (ATP)
Contains DNA and can direct the synthesis of some proteins
Ribosomes
Responsible for the production of proteins
Made up of ribosomal ribonucleic acid (RNA)
Found “free” in the cytoplasm or bound to endoplasmic reticulum
Endoplasmic Reticulum (ER)
Network of channels
Rough ER has ribosomes attached to it
-Responsible for synthesis and processing of proteins, and transporting them to the Golgi apparatus
Smooth ER lacks ribosomes
-Responsible for the synthesis of lipids and the detoxification of substances
Golgi apparatus
Six or so stacked membranous sacs called cisternae
Responsible for processing, packaging, and transporting proteins that were synthesized by the rough ER
Vesicles
Small membrane-bound sacs
Responsible for transport various substances in the cell as well as to the cell membrane for export out of the cell
Lysosomes
Small membrane bound sacs that contain lytic enzymes
Responsible for destroying and digesting proteins, carbohydrates, nucleic acids, and foreign particles
Peroxisomes
Contain peroxidases
Responsible for the production of hydrogen peroxide that is toxic to cells
Centrioles
Two cylindrical organelles near the nucleus
Responsible for separation of the chromosomes during mitosis and meiosis
Simple Diffusion
Movement from an area of high concentration to an area of low concentration, down a concentration gradient
No energy is required
no carrier molecule
Facilitated Diffusion
movement is down the concentration gradient and no energy is required - need carrier molecule
Molecules like glucose, potassium, and sodium use a carrier molecule to facilitate movement across the membrane
Osmosis
low to high
Passive process and no energy is required
when there is an unequal distribution of water on either side of a selectively permeable membrane
Osmotic pressure
force exerted on a selectively permeable membrane
Filtration
Passive process whereby molecules are moved across the membrane because of greater pressure on the side where particles are leaving
In the body filtration is powered by the blood pressure
Isotonic
equal concentration of solutes (dissolved substances) and solvent (water) inside and outside cell; cell shape is maintained
Hypotonic
higher concentration of water (lower concentration of solutes) outside cell; water moves into cell causing it to swell and eventually lyse
Hypertonic
lower concentration of water (higher concentration of solutes) outside cell; water moves out of cell causing it to shrink or crenate
Active Transport
Requires energy (ATP) and typically molecules move from an area of low concentration to an area of high concentration Requires a protein carrier (often called pumps)
Endocytosis
Energy is required
Cell membrane encloses a substance (to large for diffusion) outside of the cell forming a vesicle and then invaginates
Phagocytosis = larger molecules brought into the cell
Pinocytosis = liquid brought into the cell
Exocytosis
Energy is required
Opposite of endocytosis, the movement out of the cell
a vesicle fuses with the plasma membrane as secretion (expulsion) occurs
Transcytosis
Combination of endocytosis and exocytosis going on simultaneously
Apoptosis
Programmed cell death”
Destroys cells that may have mutated and pose the danger of becoming a cancer
It also helps to delete those immune cells that may recognize our own body as foreign
Some specialized cells no longer go through the cell cycle
Muscle cells
Nerve cells
Interphase
About 90% of a cell’s life is spent in interphase
Major events during interphase
Replication of DNA
Before replication, the two strands of DNA are hydrogen bonded together
Parental DNA strands unwind (hydrogen bonds are broken)
New complimentary nucleotides pair with nucleotides in the parental DNA strands and DNA polymerase joins the new nucleotides
When replication is complete, two identical double helix molecules have been formed
Each strand of this double helix is equivalent to a chromatid
Prophase (before)
Chromatin is condensing to form chromosomes; each consists of two identical sister chromatids joined near the center by a centromere
Centrioles move to opposite ends of the cell and spindle fibers attach the centrioles to the centromeres of each of the chromosomes
Metaphase (between)
Chromosomes line up at the middle of the cell along an imaginary line called the metaphase plate or equatorial plate
Anaphase (without)
Spindle fibers that attach the centromere to the centrioles shorten and drag the sister chromatids to opposite ends of the cell
Telophase (end)
Nuclear envelope starts to form around the chromosomes that start to unwind to form the threadlike chromatin
How many times can a cell replicate
zero to roughly 50-75 divisions
Labile cells
Ability to constantly divide
Skin cells, cells lining the gastrointestinal tract, and blood cells in the bone marrow
Stable cells
Divide when necessary
Hepatocytes (liver cells) have the ability to multiply when the liver is injured
Permanent cells
Do not have the ability to multiply A neuron (nerve cell) is an example of this type of cell
Necrosis
Pathological cell death Myocardial infarction (heart attack) results in the necrosis of cardiac muscle cells
Atoms
The smallest intact component of all matter
The basic unit of an element that enters into a chemical combination
Cannot be broken down into any simpler form of matter
3 main particles (subatomic particles):
Protons - positively charged (+)
Neutrons - no charge
Electrons - negatively charged (-)
Atomic Number
Number of protons in the nucleus of an atom (Positive charge)
(Atomic Number = number of electrons)
Number of protons (+) = Number of electrons (-) neutral charge
Mass Number
Total number of Protons + Neutrons in the nucleus (P + N)
Atomic number + number of neutrons
Number of neutrons = difference between the mass number and atomic number
Isotopes
Atoms that have the same Atomic Number but different Mass Number
Atoms with the same number of Protons, but different number of Neutrons
Electron’s Energy Level
amount of energy required by an electron to stay in orbit
Each shell can hold a maximum number of electrons
This can be determined by the formula X = 2n2
X is the maximum number of electrons in energy number n
n represents energy level / shell number
1st level - 2,
2nd level - 8
3rd level - 8
4th level - 2
Periodic Table
Elements are arranged in order of increasing atomic number from left to right
Atomic number shown above the symbol
Elements are arranged horizontally in rows called periods
The vertical columns are called groups/families
1st smallest number is the atomic number
the symbol is the atomic symbol
the lowest number is the atomic mass
Element -
cannot be broken down into simpler substances even by a chemical reaction
Basic Categories on periodic table :
Metals
Nonmetals
Metalloid
Noble Gases
Metals:
Chemical elements that are good conductor of both electricity and heat
Exist as solids at room temperature (except mercury)
Form cations and ionic bonds with non- metals
Metals occupy the bulk of the periodic table
macronutrients
protein carbs, fats
Sodium (Na), Potassium (K), Magnesium (Mg), Calcium (Ca), Chloride (Cl)
micronutrients
minerals in the body
Iron (Fe), Cobalt (Co), Copper (Cu), Zinc (Zn), Fluoride (F
Non-metals:
Poor conductors of heat and electricity when compared to metals
Exist as solids, liquids and gases at room temperature
They form acidic oxides (whereas metals generally form basic oxides)
Nonmetals – recevies electrons
Metals-give off electrons
Metalloids:
diagonal separation of metals and non-metals
Have properties of both metals and nonmetals
Metalloids often behave as semiconductors
Can carry an electric charge under special conditions
This property makes metalloids useful in computers and calculators
Molecules
An electrically neutral group of at least two or more atoms
Can be of the same or different nonmetal elements – held together by covalent bonds
Proteins
Proteins are required for building and repair of body tissues
Involved in structural support & bodily movement
Can also be a source of energy
made of amino acids
contain Carbon, hydrogen, oxygen and nitrogen
Immunoglobulins –
Antibodies that defend the body against infectious agents
Transport proteins – hemoglobin and myoglobin
The structure of a protein determines its function
amino acids
end products of protein digestion are amino acids
Amino acids are joined together by peptide bonds between the carboxyl and amino groups (amine)
Growth, repair and maintenance of all cells depends on amino acids
The synthesis of body proteins, including plasma, intracellular and structural protein
Primary protien
The sequence (linear) in which amino acids are lined up and connected by peptide bonds
Dipeptide – Two amino acids combine
Polypeptide – Many (> 3) amino acids combine
The long repetitive sequence of amino acids that make a continuous chain is called the protein’s backbone
Secondary protein
Twisting or folding of the protein chain (primary) into a spiral or coil
Called α helix; or parallel strands – called β pleated sheet
Held by hydrogen bonds between the H of the NH of one amino acid and the O of the C=O of another amino acid
Tertiary
Protein chains folded into specific three-dimensional shape held by:
Hydrogen bonds
Ionic bonds
Disulfide bonds (-S-S- bonds)
This shape is vital for the function of enzymes and the biological activity of other proteins
Quaternary
noncovalent interactions
Combination of several protein units (subunits) with its own complete structure
Example – Hemoglobin
RNA- Ribonucleic acid
A chain of nucleotides produced by transcription of DNA
Ribose C5H10O5
Single chain or strand
The sugar is ribose and the base thymine is replaced by uracil
Adenine is always bounded to Uracil
RNA is made up of – nucleotides (with a nitrogenous base), a ribose sugar, and a phosphate group
RNA – transfer information from DNA to the ribosome
Transcription of information
When a particular protein is needed by a cell –
DNA chain separates
One chain act as a template for RNA
DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA (mRNA)
In other words, the transfer of genetic information from DNA into RNA
Codon
Grouping of three nucleotides on a mRNA molecule
Codes for one of the 20 natural amino acids
mRNA / messenger RNA
Contain/carry the information on the primary sequence of amino acids in a protein to be synthesized (in the cytoplasm)
tRNA / Transfer RNA
“reads” the mRNA codon by using its own anticodon
carries the amino acid to be incorporated into the developing protein
each tRNA is specific for a certain amino acid
rRNA / Ribosomal RNA
rRNA and protein combine to form a nucleoprotein called a ribosome
Ribosome serves as the site and carries the enzyme necessary for protein synthesis
Carbohydrates
Major food source and energy supply for the body
Stored in the liver and muscle as glycogen
The primary way for cells to obtain energy is through the oxidation of carbohydrates – ATP
Supply carbon for the synthesis of cell components
Organic compounds containing only C, H and 0
Ratio of carbon, hydrogen and oxygen is 1:2:1
Functional groups - an aldehyde (aldose)—(O=CH) or ketone (ketose)—-(O=C)
Citric Acid Cycle
Polysaccharides such as starch and glycogen are first hydrolyzed by enzymes to Glucose
Glucose is transported by blood in animals and cell sap in plants
Glucose is then oxidized to produce carbon dioxide and water
Energy is released in this process which is used for functioning of the cells
Energy can be extracted from carbohydrates, fats and when necessary, proteins
Reducing substances:
educe other compounds
Must contain ketone or aldehyde group
e.g. glucose, maltose, fructose , galactose and lactose
Formation of Gylcosidic bond
With other carbohydrates or non carbohydrates e.g. 2 sugar molecule
Simple sugars
Monosaccharides
Disaccharides
Example: Sugar found in candy, jams and most desserts
General formula: Cn(H2O)n
n can be 3, 5 , 6 carbon atoms
Glucose (C6H12O6) , fructose and galactose
hexose sugars are the most abundant simple sugars and those most frequently found in food
Disaccharides
Combination of two simple sugars linked by a glycosidic bond (covalent bond)
Involves the elimination of water, from the functional groups only
Produce two monosaccharides when react with water
Common disaccharides:
Maltose —– 2 D-glucose molecules
Lactose—— glucose + galactose
Sucrose—— glucose + fructose
Polysaccharides
Important polysaccharides
Starch, glycogen, cellulose
Starch
Humans are able to metabolize
Produced by plants for storage
Cellulose
Plant stems and leaves
Humans are not able to metabolize
Glycogen
Composed of a large number of glucose units
Humans store energy/glucose in the form of glycogen
Stored in the liver and muscles
Lipids
Main biological function of lipids include energy storage
Lipids are a class of hydrocarbon - containing organic compounds
Contain the same elements as carbohydrates but with much less oxygen
Part of cell membrane
Precursor for steroid hormone
Lipids / (Fats)
hey are insoluble in water
They are soluble in nonpolar organic solvents (such as ether and chloroform)
Esters of long chain organic acids called fatty acids
Fats are formed by the reaction of fatty acids and glycerol (alcohol)
Glycerol occurs naturally in the body as a component of stored fat
most abundant lipids in the body
triglycerides - Consist of three molecules of fatty acids combined with a molecule of glycerol
Only small amount of lipids in plasma
Lipids with fatty acid: triglycerides
Lipids without fatty acids: steroids
Saturated Fats
They tend to be solids and are referred to as fats
Fatty acids in these fats have single bonded carbons
Unsaturated Fats
They tend to be liquids and are called oils
Fatty acids in these fats have some double bonded carbons
Phospholipids
They form the major components of the cell membrane — Phospholipids and glycolipids
Form lipid bilayers
Structure:
Contain a phosphate group
Esters of glycerol with two fatty acids and one phosphate-nitrogen compound
Free fatty acids
They are released when fats are broken down – hydrolysis of fat
They are increased in conditions where sugar is not being used
Low blood sugar; diabetes, starvation, etc
Steroids
Functions include:
Form part of the cell membrane
Form part of the bile salts which emulsify fats during digestion
Form the ‘steroid’ hormones
Cholesterol – Found in the cell membranes and transported in the blood
Cortisol – Stress hormone
Aldosterone – Regulates salt excretion
Estrogen, progesterone and testosterone – sex hormones
Unlike other lipids they are not esters
Cholesterol
Part of plasma membrane
Made by the liver
Supplied with food
Must be bound to protein to be transported through the blood (LDL, HDL)
Amphipathic molecule - Polar head, and a nonpolar tail
Insoluble
LDLs
(low-density lipoproteins) – transport cholesterol from the liver to other cells of body
Tends to deposit cholesterol on arterial walls
HDLs
(high-density lipoproteins) – removes cholesterol from dying cells and return it to the liver
Carry cholesterol effectively and can dissolve cholesterol deposits in the arteries