Module 3 Flashcards
light energy is used to help visualize a specimen and magnify it so that parts or entire organisms that are not visible to our eye can be seen. Organisms can be viewed while still living and the image is in real color. Beam of light
Light Microscope
the process of enlarging an object in appearance.
Magnification
the ability of a microscope to distinguish two adjacent structures as separate: higher resolution, better the clarity and detail of the image.
Resolving Power
Frog Eye, Salt Granule, Paramecium, Plant Cell, E.Coli, Red Blood Cell, Flu Virus
What can be seen using a light microscope?
allows us to see things that are far smaller than can be viewed in a light microscope because they bounce electrons off the surface of the specimen instead of using larger light photons. Specimens require special treatment. You aren’t able to see living organisms and the images are in black and white. A beam of electrons.
Electron Microscope
electron beam penetrates the cell and provides details of a cell’s internal structure. Restricted to a layer of the cell. High resolution of sliced specimens.
Transmission Electron
a beam of electrons moves back and forth across a cell’s surface, creating details of cell surface characteristics. If split open, it provides surface images of inside the cell.
Scanning Electron Microscopes
Plant cell, Red Blood Cell, E.Coli, Flu Virus, Hemoglobin, Antibody, DNA,
What can be seen using an electron microscope?
recognizing the fundamental nature of cells as the units of life.
Cell Theory
All organisms consist of one or more cells.
The cell is the basic unit of life.
All cells arise only from pre-existing cells.
Three Main Generalizations of the Cell Theory
Cytoplasm, Plasma Membrane, Ribosomes, Nucleus, Mitochondria, ER, Golgi, Cell Wall, Central Vacuole, Chloroplast.
Plants
Cytoplasm, Plasma Membrane, Ribosomes, Nucleus, Mitochondria, ER, Golgi, Cell Wall (some), Central Vacuole (some), Chloroplast (some).
Protist
Cytoplasm, Plasma Membrane, Ribosomes, Nucleus, Mitochondria, ER, Golgi, Cell Wall.
Fungal
Cytoplasm, Plasma Membrane, Ribosomes, Cell Wall.
Bacterial
Cytoplasm, Plasma Membrane, Ribosomes, Nucleus, Mitochondria, ER, Golgi.
Animal
Cytoplasm, Plasma Membrane, DNA, and Ribosomes
ALL CELLS
Nucleus, Miochondria, ER, and Golgi
ALL Eukaryotes
Cell Wall, Central Vacuole, and Chloroplast
ALL plants, not at all in animals, and sometimes in others (Protists).
small cells with no internal organelles, live in every possible habitat, found in Archaea and Bacteria.
Prokaryotic Cells
large cells with many organelles that are part of a much larger multicellular organism, classified as a Kingdom within the Domain Eukarya.
Plant Cells and/or Animal Cells
small to large cells, single or colonial, contain many organelles, highly diverse, found in autotrophic and heterotrophic organisms, classified as a Kingdon within the Domain Eukarya.
Protistan Cells
large cells with many organelles that are part of a much larger multicellular organism, multinucleate (more than one nucleus), classified as a Kingdom within the Domain Eukarya.
Fungal Cells
Which cell type can perform all the chemical “jobs” of a cell most efficiently.
Eukaryotes because they have organelles to carry out different reactions.
Internal membranes enclosing their DNA (a nucleus) and other organelles.
Cytoplasm, Plasma Membrane, Ribosomes, Nucleus, Mitochondria, ER, Golgi in all Eukaryotes.
Cell wall, Central Vacuole, and Chloroplast in some Eukaryotes (all in plants, some in protists, and cell wall only in fungi).
Many organelles
Multicellular organisms
Kingdom within the Domain Eukarya
Larger cell size
Intracellular transport.
The study of the structure and function of these surfaces.
Eukaryotes
membrane bound compartments within a cell that function much like the organs of an animal.
Organelles
Make up of phospholipid bilayer with embedded proteins that separates the internal contents of the cell.
Controls the passage of organic molecules, ions, water, and oxygen into and out of the cell.
Waste exits the cell by passing through the plasma membrane.
Semipermeable – certain substances can pass through
Proteins, glycoproteins (proteins with carbohydrates attached), cholesterol (type of lipid) = Eukaryotes
Structure is stabilized by ergosterol (steroid molecule related to cholesterol) = Fungi
Plasma Membrane
Most prominent organelle in a cell.
Houses the cell’s DNA.
The information in DNA Directs the synthesis of ribosomes and proteins.
Semi-solid fluid inside the nucleus, Nucleoplasm, which contains a nucleolus and chromatin.
nuclear envelope, chromatin and chromosomes, and a nucleolus are found here.
Nucleus
double-membrane structure that constitutes the outermost portion of the nucleus. Inner and outer membranes are phospholipid bilayers. Pores control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm
Nuclear Envelope
are structures within the nucleus that are made up of DNA packaged with proteins.
Linear structures, every eukaryotic species has a specific number of these, only visible and distinguishable from one another when the cell is getting ready to divide.
Growth and maintenance phases look like a jumbled bunch of threads.
Chromosomes
the protein-chromosome complexes that make up the chromosomes.
Chromatin
The region of a cell between the plasma membrane and the nuclear envelope.
Consists of gel-like cytosol, organelles, the cytoskeleton, and various chemicals.
Mostly made up of water (70-80%)
Semi-solid consistency because of the large numbers of proteins within it.
Organic molecules: glucose, simple sugars, complex carbohydrates, amino acids, nucleic acids, fatty acids, and derivatives of glycerol.
Ions: sodium, potassium, calcium, etc.
Protein synthesis and other metabolic reactions take place in the cytoplasm.
Cytoplasm
Are the site of protein synthesis.
Appear as clusters or single, tiny dots that float freely in the cytoplasm.
Attached to the cytoplasmic side of the plasma membrane or rough endoplasmic reticulum or the outer membrane of the nuclear envelope.
Two subunits, large and small.
Receive their “orders” from protein synthesis from the nucleus, which is where DNA is transcribed into messenger RNA (mRNA), then the mRNA travels to the ribosomes, which translates the code in the mRNA into a specific protein.
Found in EVERY cell.
There are a ton of ribosomes in cells that synthesize large amounts of proteins.
Ribosomes
Powerhouse or energy factories – they are responsible for making adenosine triphosphate (ATP)
Cellular respiration is the process of making ATP using the chemical energy found in glucose and other molecules.
Uses glucose and oxygen and produces water and carbon dioxide as a waste product.
Muscle cells have lots of these.
Oval shaped organelles surrounded by a double membrane which contains its own DNA and ribosomes.
Inner layer has folds called cristae.
Area surrounding the folds called mitochondrial matrix.
Mitochondria
a type of nucleotide and is the main short-term energy storage molecule.
ATP
Both are membrane-bound sacs that function in storage and transport.
Transport, lysosomes, peroxisomes, secretory
Vesicles
move materials around inside the cell, from one organelle to the next.
Transport Vesicles
enzymes that breakdown waste products (only found in animal cells).
Lysosomes
use oxygen to break down fatty acids, amino acids, and detoxify poisons.
Peroxisomes
fuse with the plasma membrane to release waste or produces of a cell (hormones).
Secretory Vesicles
larger than vesicles
deal with water balance in a cell.
More common in plant, fungal, and some protistans cells.
When it shrinks, the cell wall is unsupported.
Lose of support to the cell wall – wilted appearance to the plant
Expansion of the cell – hold more water, the cell gets larger without having to invest a lot of energy in synthesizing new cytoplasm.
Vacuoles
It regulates the cell’s concentration of water in changing environmental conditions.
Central Vacuole
Made up of different types of protein that form different sized tubules with different functions.
Separation of the chromosomes and cytoplasm during cell division
Cytoskeleton
form the cilia and flagella that allow cells to “swim” or move materials around the outside of the cell by creating currents.
Microtubules
short and numerous
Cilia
longer and singular
Flagella
Plants, fungi, and some protists.
Ridged covering that protects the cell, provides structural support, and gives shape to the cell.
Prokaryotic cell walls: peptidoglycan
Cell Wall
Have their own DNA and ribosomes.
Found in plants and some protists that carry out photosynthesis.
Outer and inner membranes
Within the space enclosed by the inner membrane there is a set of interconnected and stacked fluid-filled membrane sacs called thylakoids.
Each thylakoids sack is called a granum.
The fluid enclosed that surrounds the granum is called the stroma.
Green pigment = chlorophyll
Chlorophyll – captures the light energy that drives the reaction of photosynthesis.
Chloroplasts
Understand the structural differences between animal and plant cells, and describe how these structural differences affect cell functions.
There are three components that make the plant cell and animal cell different from each other. The plant cell has a cell wall, central vacuole, and chloroplast where the animal cell does not. The cell wall helps maintain the cell shape. The central vacuole is filled with cell sap that maintains pressure against the cell wall. The chloroplast is where photosynthesis occurs; animals are not photosynthesizers.
evolved at least partially through some cells engulfing and retaining other cells nearly intact. Mitochondria and chloroplasts are the organelles with this origin. An ancestor of modern eukaryotes engulfed an aerobic bacteria and they then co-evolved to become dependent upon each other. Later, one lineage of mitochondria-containing eukaryotes engulfed a photosynthetic bacteria that became the chloroplasts of plants and some protists.
Endosymbiotic Theory
double membranes – derived from the original prokaryotic inner and outer cell membranes.
Their own chromosomes that are circular like those in prokaryotes. DNA sequencing data shows they are more similar to certain modern bacteria than they are to eukaryotic genes.
Ribosomes that are smaller than the ones in their eukaryotic host cells and that are the same size as prokaryotic ribosomes.
Undergo binary fission, not constructed by the cell in which they live.
Endosymbiotic Theory Evidence
Located in the nucleus, 1+ charge
protons
located in the nucleus, 0 charge
neutrons
located in the orbitals, 1- charge
electrons
Atoms are more stable when they gain or lose an electron and form ions.
Fill their outermost electron shell.
When the electrons don’t equal the number of protons, each ion has a net charge.
Cations are positively charged ions and they are formed by losing electrons.
Anions are negatively charged ions that are formed by gaining electrons.
Formed between ions with opposite charges.
Not as strong as covalent bonds when in water (ionic bonds are weak in water because water can interact with the charges = why table salt dissolves in water).
Ionic Bonds
the strongest bons because the two atoms are sharing a pair of electrons which orbit both.
They are strong enough to hold molecules stably together in water.
Some bonds can be polar/polar water can form these bonds.
Individually weak But are important because they are Very numerous inside cells
Occurs when atoms share electrons and are much more common than ionic bonds in the molecules of living organisms.
The more covalent bonds the stronger their connection.
Hydrogen and oxygen atoms that combine to form water molecules are bond together.
Polar and Nonpolar
Covalent Bonds
the electrons are unequally shared and are attracted more to one atom than the other. A slightly positive and slightly negative charge developed. Water/Hydrophilic
Polar
has an affinity for water (charged ions and polar molecules)
Hydrophilic
Form between two atoms of the same element or between different elements that share electrons equally. (O2) is nonpolar because the electrons will be equally distributed between the two oxygen atoms.
Hydrophobic
Nonpolar
no affinity for water (nonpolar molecules) Fatty acids
hydrophobic
The electrical attraction of a positively charged hydrogen of one molecule to the negatively charged region of another molecule.
Weaker bonds.
Provide many of the critical, life-sustaining properties of water and also stabilize the structures of proteins and DNA.
Slightly positive, it will be attracted to negative charge.
A weak interaction occurs between S+ charge of the hydrogen from one molecule and the S- charge on the more electronegative atoms of another molecule, usually oxygen or nitrogen, or within the same molecule.
Single hydrogen bonds are weak and easily broken.
Large numbers of water and large organic molecules create a major force in combination.
Hydrogen Bonds
makes up at least 70% of our body.
Most abundant molecule
polar.
these molecules attract other water molecules forming hydrogen bonds.
attracted to other polar molecules and ions.
Hydrophilic – dissolves in water, like water.
Hydrophobic – don’t interact well with water, don’t like it.
75% of the weight of a cell
Major constituent of the cytoplasm.
water
the scale by which we record the probability that a hydrogen bond between water molecules can be strong enough for one molecule to pull the hydrogen atom away from the other.
A simpler and more common definition is a measure of the concentration of H+ ions [H+] in a solution.
pH measures
pH = -log[H+] – [H+] is the probability that hydrogen atoms are freed to form hydronium/concentration of H+ measured in moles/liter
pH Equation
Start as two water molecules and then are transformed into hydroxide and hydronium.
pH
a substance that increases the concentration of hydrogen ions in a solution, usually by having one of
HCl + H2O –> H+ + Cl- + H2O
Acid
provides either hydroxide ions or other negatively charged ions that combine with hydrogen ions, reducing their concentration in the solution and thereby raising the pH. Strong bases are those substances that readily donate OH- or take up hydrogen ions.
NH3 + N+ + OH- –> NH4+ + OH-
Base
anything below 7 is acidic and anything about 7 is alkaline. 7 is normal neutral. Anything that extremes in pH in either direction from 7 is usually inhospitable to life.
Using the negative logarithm to generate positive integers, high concentrations of hydrogen ions yield a low pH number, whereas low levels of hydrogen ions result in a high pH.
Logarithmic Scale
monomers are bound together by covalent bonds to form polymers in a chemical reaction.
This causes the OH from one monomer and the H from another to form water as the two monomers bind.
Water is a product of the reaction and is released into the solution.
When the bonds are forming together, monomers release water molecules as byproducts.
Monomers share electrons and form covalent bonds.
Forms new bonds, requiring energy.
Condensation
The covalent bonds of polymers are broken in the reverse reaction.
This is because water is broken apart or “lysed” to form the OH and H that attach to the separated monomers.
Water is a reactant of this reaction and is removed from the solution.
Broken down into monomers, which means “to split water.”
A reaction in which a water molecule is used during the breakdown.
During the reactions, the polymer is broken into two components: one gains a hydrogen atom (H+) and the other gains a hydroxyl molecule (OH-) from a split water molecule.
Break bonds and releases energy.
Hydrolysis Reaction
a small molecule that can combine with others just like it, or that are only slightly different, to form larger molecule structures.
Can be bound together by covalent bonds to form polymers in a chemical reaction.
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Reducing sugars
Monomers
large molecules that can be broken down into smaller, separate, but very similar molecules. Starch
Polymers
Simple sugars, Complex carbohydrates, Sugars have basic formula (CH2O)n
Carbohydrates
monosaccharide like glucose or other similar small sugar
Carbohydrates Monomer
polysaccharide like cellulose, starch, glycogen and chitin – many different kinds and shapes.
Carbohydrates Polymer
structure & energy storage, supports cell, provides quick energy
Carbohydrates Function
complex polysaccharides
Carbohydrates Structure
cytoplasm and cell wall.
Carbohydrates Location
simple mono- and disaccharides, complex polysaccharides
Carbohydrates Energy
triglycerides (fats and oils), phospholipids, sterols and steroids, and waxes, molecules that are nonpolar and insoluble in water.
Lipids
there is no one single monomer for lipids, though many contain glycerol and/or fatty acids
Lipids Monomer
fats, oils, and steroids and phospholipids– many different kinds and shapes
Lipids Polymer
steroid hormones
Lipids Signaling
store energy, structure (cell membranes), and signaling between cells.
Lipids Function
cytoplasm, plasma membrane, intracellular membranes.
Lipids Location
triglycerides (fats and oils) (made of glycerol + 3 fatty acids)
Lipids Energy
waxes, phospholipids for plasma membranes (phospholipids = glycerol + hydrophobic fatty acids + hydrophilic head group)
Lipids Structure
defines the cell, outlines its borders, and determines the nature of its interaction with its environment.
Cell’s Plasma Membrane
flexible to allow certain cells, like red and white blood cells, to change shape as they pass through narrow capillaries.
carries markers that allow cells to recognize one another, which is important for tissue and organ formation during early development.
Ability to transmit signals by means of complex, integral proteins known as membrane receptors. These proteins act as receivers of extracellular inputs and as activators of intra cellular processes.
Structural Components of Cell Membranes
describes the structure of the plasma membrane as a mosaic of components that give the membrane a fluid character. The two major structural components are lipids and proteins. Phospholipids create the structure of the membrane (lipid bilayer) and give the membrane its barrier function because water and water soluble molecules can’t cross lipid bilayer. Proteins are like the floating tiles of the mosaic, floating in the sea of phospholipids.
Fluid Mosaic Mode
spontaneously form lipid bilayer in water (to hide nonpolar tails and allow hydrophilic heads to interact with water) Provide barrier function of the membrane by blocking diffusion of water/water soluble solutes.
Phospholipids
other functions of membrane = allow movement of solutes across membrane, also enzymes, receptors, etc.
Protein
Helps digest food by breaking polymers into monomers.
Make polymers from monomers.
Carry substances in the blood or lymph throughout the body.
Compose structures that support cell organelles (cytoskeleton) or body parts (cartilage)
Coordinate the activity of different body systems.
Protect the body from foreign pathogens.
Muscle contraction.
Provide nourishment in early development of a seedling or embryo.
Transport small molecules/ions.
Signals and receptors – carry and receive messages between cells.
Defense – protect body from pathogens.
Function/Roles of Proteins
are polymers but are made up of amino acids which are monomers.
Proteins
Enzyme can bind to a specific substrate at a site known as the active site.
If the active site is altered because of local changes or changes in the overall structure, the enzyme my be unable to bind to the substrate.
Dependent on four levels, primary, secondary, tertiary, and quaternary.
Sequence –> Shape
–> Function
If a protein isn’t present, the protein test will be a negative result like the starch. When conducting the experiment, we notice that the chemicals changed to a lavender/violet color when proteins were present.
During the experiment we had two controlled variables (+ and -) (+ control: albumin, - control: starch) and we had two positive variables (active amylase and boiled amylase).
Hydrogen bonds hold the proteins shape.
Protein Structure
monomers that make up proteins.
Covalent bonds hold amino acids together
Same fundamental structure, central carbon atom bonded to an amino group, a carboxyl group, and a hydrogen atom.
Has another atom or group of atoms bonded to the central atom known as the R group.
20 amino acids are present in proteins.
R group is different.
Single uppercase letter or three-letter abbreviation.
Chemical nature of the side chain determines the nature of the amino acid (polar, nonpolar, acidic, basic)
Essential amino acids refer to those that the body cannot make but are needed for construction of proteins in the body.
Human require 9 essential amino acids.
Proteins are made when the carboxyl group of one amino acid and the amino group of the other amino acid combine, releasing a molecule of water (condensation reaction). The resulting connection is a type of covalent bond called a peptide bond. As more amino acids join to the growing chain, the resulting molecule is known as a polypeptide.
Amino Acids
The sequence of amino acids in a chain
Primary
hydrogen bonding of the peptide backbone causes the amino acid chair to fold into a repeating pattern
Secondary
three-dimensional folding pattern of a protein due to hydrogen bonding and side chain interaction
Tertiary
protein consisting of more than one amino acid chain held together by hydrogen bonds.
Quaternary
a substance that helps a chemical reaction to occur Specifically, it speeds up the overall rate of the reaction
Catalyst
the special molecules that catalyze biochemical reactions.
Almost all of these are proteins, and they perform the critical task of lowering the activation energies of chemical reactions inside the cell.
Enzymes
the amount of energy required for that specific reaction to occur.
when lowered, the reaction can occur quickly.
happens when enzymes bind to the reactant molecules and hold them in such a way as to make the chemical bond-breaking or bond-forming processes take place more readily.
They only reduce the activation energy needed for the reaction to occur.
Enzyme’s Substrates (one or more) are the chemical reactants to which an enzyme bind.
Condensation reactions that form the covalent bonds of polymers and the hydrolysis reactions necessary to break those covalent bonds are catalyzed by enzymes.
Activation Energy
Types of reactions catalyzed by enzymes
condensation, hydrolysis, digestion , DNA replication, breaking down toxins in the body
Enzyme binds substrate in the enzyme’s active site, lower the activation energy as you described and catalyzes the reaction so it will occur rapidly. (Very quickly, the average is 1000 reactions/second per enzyme)
In addition, the enzyme is re-usable. Catalyzing the reaction doesn’t permanently change the enzyme, so it will be able to catalyze that reaction again and again.
Process of enzyme-catalyzed reaction
the location within an enzyme where the substrate binds. And the reaction is catalyzed
Unique combination of amino acid R groups within the active site. So, for an enzyme to function you need the right primary structure (sequence) AND it must be properly folded to create the active site.
Active Site
large or small, weakly acidic or basic, hydrophilic or hydrophobic, positively or negatively charged, or neutral.
R Groups
as enzyme and substrate come together, their interaction causes a mild shift in the enzyme’s structure that forms an ideal binding arrangement between the enzyme and the substrate. This maximized the enzyme’s ability to catalyze its reaction.
Enzyme Function/Induced Fit Model
The complex (enzyme binds its substrate) lowers the activation energy of the reaction and promotes its rapid progression in one or many ways.
Enzymes promote chemical reactions that involve more than one substrate by bringing the substrates together in an optimal orientation.
Enzymes promote the reaction of their substrates by creating an optimal environment within the active site for the reaction to occur.
Enzyme Function
Increase in the environmental temperature – increase reaction rates. For small changes in temperature that don’t denature the enzyme.
Increasing or decreasing the temperature outside of an optimal range can affect chemical bonds within the active site in such a way that they are less well suited to bind substrates.
High temperatures will eventually cause enzymes to denature. By breaking the hydrogen bonds of the folded structure
Denaturing causes the shape of the enzyme to change and the active site to cease to exist.
Active site amino acids have their own acidic properties that are optimal for their function.
Amino acids are sensitive to changes in the pH that can impair the way substrate molecules bind.
Enzymes are to function best within a certain pH range.
Temperature and extreme pH values can cause enzymes to denature and the rates of the reaction decrease.
environmental conditions can influence protein structure and the shape of the active site of an enzyme
solutions made up of a weak acid and weak base in proportion s that allow the absorption of free hydrogen ions and free hydroxide ions.
help organisms keep pH within the necessary range.
Buffers absorb excess H+ and OH-, keeping the pH of the body carefully maintained in the narrow range required for survival.
Cells use buffers to maintain a relatively constant internal environment because many important cellular functions only take place within a narrow range of conditions.
Enzyme’s function is influenced by the pH of its environment and it only functions optimally within a narrow pH range.
help maintain the correct pH for the functioning of a cell.
Buffers
When temperature is high
it denatures the structure and therefore the enzymes don’t work.
When pH is lower
it denatures the structure and therefore the enzymes don’t work.
When temperature is lower
there is less breaking of the hydrogen bonds, and it slows down the process.
_____________________ found in the stomach and ____________ found in the small intestines
pepsin, trypsin
might have a different pH level to help break down or support the enzymes found within that region, the stomach or small intestines. Each of these have a different function for the body which will affect their pH levels. Having different pH levels will help these body parts function to the best of their abilities.
pepsin and trypsin
Explain why cell division is necessary for living organisms.
Cell division is important because it allows living organisms to grow, reproduce, and repair themselves.
the cell grows and DNA is replicated
Interphase
initial growth phase. Cell grows and prepares for DNA replication. Grow, check DNA, and prepare for replication.
G1
Is my DNA okay? Make certain that a cell is large enough and has enough resources to divide, and that there’s been no damage to the DNA.
G1 Checkpoint
DNA synthesis. DNA replication results in the formation of two identical copies of each chromosome (sister chromatids)
S
second growth phase. Cell continues to grow and prepares for mitotic phase. Grow, check DNA, prepare for mitosis.
G2
Is my DNA replicated? Make sure all the DNA was replicated appropriately and that all the resources needed for division are available. This is another place where they check on cell growth
G2 Checkpoint
replicated DNA and contents of the cytoplasm are separated and the cell divides.
Mitotic Phase
division of nuclear material. Replicated chromosomes are aligned, separated, and moved to opposite poles of the cell. Divide DNA equally.
Mitosis
when cells make certain that each chromatid is connected to the appropriate spindle fiber.
Mitotic Checkpoint
division of cytoplasm. Physical separation of the cytoplasmic components into two daughter cells. Divide entire cell.
Cytokinesis
DNA and RNA are made up of these monomers.
Combine with each other to form a nucleic acid.
Made up of three components: nitrogenous base, a pentose sugar, and one or more phosphate groups.
ATP is an example, and it is a short-term energy source for all cell
Adenine (A), guanine (G), cytosine (C), and thymine (T)
Nucleotides
Four types of Nucleotides in DNA
Adenine (A), guanine (G), cytosine (C), and thymine (T)
Which nucleotides are purines (two carbon-nitrogen rings)
Which are pyrimidines (single carbon-nitrogen ring)?
A and G
C and T
Which nucleotides go together?
A and T
C and G
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Nucleic Acid
genetic material found in all living organisms, ranging from single celled bacteria to multicellular mammals. Never leave the nucleus of eukaryotic cells, but instead use an intermediary to communicate with the rest of the cell.
DNA
protein synthesis, leaves the nucleus, single stranded, ribose
RNA
double helix structure
backbone of the molecule (outside of the helix) sugar and phosphate (held together by phosphodiester bond which are strong and covalent)
interior – nitrogenous bases (held together by hydrogen bonds which are weak and noncovalent)
two strands of the helix run in opposite directions, 5’ carbon end will face 3’ carbon end.
Purine can only pair with a specific pyrimidine – A and T, G and C.
DNA strands are complementary to each other.
Three subunits: five caron sugars, nitrogenous base, phosphate
DNA
Carries genetic information.
DNA Function
remain in the nucleus
DNA Location
Double helix each strand is a polymer (nucleic acid) of monomers (nucleotides)
DNA Structure
deoxyribose
DNA Sugar
cytosine, thymine
DNA Pyrimidines
adenine, guanine
DNA purines
sequence of a complementary strand of DNA will be determined by the pre-existing strand.
DNA base-pairing rules
process of copying DNA which occurs when a cell is preparing to divide.
DNA Replication
Helicase (unwind), polymerases (adds nucleotides), and ligase (seals the fragments of the lagging strand together)
Enzymes involved in DNA replication
Phase of the eukaryotic when replication occurs
S phase
breaks the hydrogen bonds between the 2 complementary DNA strands, unwinding the strands and exposing nucleotides.
Unzips
DNA helicase
adds nucleotides to the new strand using base pairing rules, added to the 3’ end of the molecule so that the new strand is constructed in a 5’ to 3’ direction
DNA polymerase
they are made in a series of short fragments
Lagging-Strand
new strand, adding nucleotides as the old DNA strand is unzipped
Leading-Strand
joins the Okazaki fragments of the lagging strands
DNA ligase
Half is the parental DNA strand while the other is the new DNA strand.
Semi-conservative
All cells grow in terms of size and accumulation of molecules needed for proper functioning and they must replicate their DNA before they are able to reproduce.
Prokaryotes have a single circular chromosome and no nucleus. When cells grow, the chromosomes is attached to the cell membrane and is replicated so that the new chromosome is also attached. Chromosomes move apart and the cell begins cytokinesis with a cleavage furrow. The two cells are separated, and the process is ready to start again.
Process of Cell Division
The big difference is that with one circular chromosome, prokaryotic cells don’t NEED mitosis. Mitosis solves a problem that doesn’t exist in prokaryotes, how to properly separate multiple individual chromosomes correctly.. The division of cells is also different because the prokaryotic cells have a cell wall that is holding their structure together so they are unable to complete the cleavage furrow process. Plant cells for a cell plate in the middle of the cell to divide and replicate the new cell.
Why plants don’t use mitosis.
More complex because they have multiple chromosomes in the nucleus.
When one cell divides, there needs to be some organization to ensure that each new cell gets an identical copy of each chromosome.
The process of organizing those chromosomes and separating them.
Mitosis is the separation of chromosomes, basically the division of the cell’s nuclear content.
Has stages because it was first observed through the microscopes using stained and fixed cells that were not alive. But it is also useful to have those labels to think about the sequence of events that must happen.
Continuous process.
Mitosis
Long stretched out strands of DNA are condensed into tight packages.
Nuclear membrane dissolves/nuclear envelope breaks down.
Centrioles move toward the cell poles.
Microtubules form between the centrioles.
Chromosomes condense and become visible.
Spindle fibers emerge from the centrosomes.
Prophase
Chromosomes line up along the equator of the cell.
Microtubules attach to the centromere of each chromosome.
Metaphase
Chromatids are separated.
Begin to move toward the poles of the cell.
Anaphase
Chromosomes de-condense.
Nuclear membranes reassemble.
Cleavage furrow begins to form in animal cells or a cell plate forms in plant & fungal cells.
Telophase
Stage of Mitosis in Order
Interphase, prophase, metaphase, anaphase, and telophase, cytokinesis.
Using a ring of actin and myosin molecules that tighten around the center of the cell and pinches it in two.
cleaver furrow
Difference in plant cells during mitosis.
cannot do cytokinesis the same because of the rigid structure of their cell walls.
After mitosis a series of membrane bound vesicles contain components of a new cell wall form between the two new nuclei.
A cell plate grows and fuses so that their contents becomes the cell walls and their membranes become the cell membranes of the two new cells.
Division of the cytoplasm.
Far less complex of a problem than division of the nucleus with its cargo of important information.
At the end, there are two cells both identical to the original.
Last step: partition out the cytoplasm and its contents.
Cytokinesis
form a contractile right that shrinks.
Cytokinesis in animal cells
deposit a cell plate (new cell wall) in the middle of the cell.
Cytokinesis in plant cells.
double-stranded DNA molecule wrapped tightly around proteins called histones. Each one contains different genetic information.
Chromosomes
paired chromosomes that carry the same genes, one from each parent.
Homologous Chromosomes
occurs during S phase. DNA replication results in the formation of two identical copies of each chromosome that are firmly attached at the centromere region.
Sister Chromatid
two bonds are held together by this to form a chromosome with two chromatids.
Centromere
occurs when any cell reproduces itself uncontrollably, usually forming a mass of these cells, many of which function inappropriately.
Doesn’t stop dividing and forms a tumor.
evade checkpoints.
continue to divide over and over again.
can survive and invade new parts of the body.
Rapid multiplication of cells/no organization during the cell cycle.
Cells stop obeying signals from normal cells.
Lose the ability to stick together
Cancer Cells
tells cells it should divide/genes for checkpoint proteins. When one or more of theses genes are damaged/mutated, the cell can no longer regulate division and becomes cancerous.
Proto-oncogene
always green regardless of conditions
Oncogene
senses problems. Stops cells at checkpoints.
Lose its function: checkpoint is lost.
Tumor Suppressor
