Midterm: Topics 1 - 6 Flashcards
A suggested explanation for a problem that can be tested such as a microorganism was causing significant fish kills in a lake would be called a
Hypothesis
What is the smallest, basic unit of life?
Cell
Homeostasis provides what kind of environment?
Constant
Organizing known species of organisms according to their evolutionary relatedness is known as
Taxonomy
What is a form of logical thinking that uses related observations to come to a general conclusion?
Inductive reasoning
A collection of tissues involved in a common function are known as
Organs
The study of the structure and function of single-celled organisms is known as
Microbiology
The type of science that is done in order to understand living things without regard to an ability to directly use that knowledge is known as
Basic science
Which is a group of the same species living in a geographical area?
Population
The idea that organisms are able to “fit” their environment due to their characteristics is known as
Adaptation
Which is the smallest portion of a substance that retains the properties of an element?
Atom
The negative subatomic particles that orbit the nucleus are
Electrons
Water is an example of a(n)
a. atom
b. ion
c. compound
d. mixture
e. element
Compound
How do hydrophobic molecules react with water?
Repelled by
Starch is
a. a polypeptide
b. a polysaccharide
c. a lipid
d. a nucleic acid
b. a polysaccharide
Carbon usually forms how many bonds with other atoms?
4
Which are NOT macromolecules (also known as polymers)?
a. proteins
b. cellulose
c. amino acids
d. nucleic acids
c. amino acids
Which of the following includes all the others?
a. sucrose
b. glucose
c. cellulose
d. starch
e. carbohydrate
e. carbohydrate
What kind of bond exists between two amino acids in a protein?
peptide
A chemical buffer
a. makes things shiny
b. equalizes ions
c. provides hydrogen ions or removes them to maintain pH
d. puts up a sphere of hydration between ions
c. provides hydrogen ions or removes them to maintain pH
The idea that mitochondria and chloroplasts likely came from a larger prokaryotic cell engulfing and enslaving a smaller prokaryotic cell is known as the _____ theory.
Endosymbiotic
Which of the following has a cell wall made up of peptidoglycan?
a. bacteria
b. plants
c. animals
d. archaea
e. all of these
bacteria
________ is responsible for making lipids (and membrane vesicles).
Smooth ER
________ are specialized storage structures in plants (can hold water for rigidity).
Central vacuole
_________ is (are) primarily responsible for moving things from one part of the cell to another.
Vesicles
_______ is the “powerhouse” of the cell, known for making ATP.
Mitochondria
_______ is the “post office” of the cell, known for sorting and sending proteins and lipids to their final destination.
Golgi
Prokaryotes do NOT have _____.
Membrane bound nuclei
_____ is a cell part responsible for maintaining cell shape, internal organization, and cell movement.
Cytoskeleton
Which type of junctions allows small molecules to pass between cells?
Gap
All of the following are associated with endocytosis EXCEPT
a. secretion of cell products
b. endocytic vesicles
c. phagocytosis
d. plasma membrane going in
e. bulk-phase uptake of materials
a. secretion of cell products
To be able to invade host cells, viruses need something to attach to, usually a cell membrane
Receptor
The concentration of glucose inside of a cell is higher than the concentration outside of that cell, yet glucose continues to enter the cell. This is an example of
Active transport
A charge difference across a membrane, like what happens with K+ and Na+, is known as the
Electrochemical gradient
Which of the following accounts for the cell membrane keeping out polar substances from the cell?
a. the hydrophilic phospholipid heads
b. the integral membrane proteins
c. the hydrophobic fatty acid tails of the phospholipids
d. the cytoskeleton
C. The hydrophobic fatty acid tails of the phospholipids
The carrier molecules (transporters) used in active transport are
Proteins
A single-celled freshwater organism is transferred to salt water. Which of the following is likely to happen?
a. the cell bursts
b. salt is pumped out of the cell
c. shrinking
d. enzymes flow out of the cell
e. all of these
c. shrinking
Which of the following is NOT likely to diffuse through a membrane?
a. glucose
b. oxygen
c. water
d. carbon dioxide
a. glucose
Which statement is NOT true?
a. membranes are often perforated by proteins that extend through both sides of the membrane.
b. some membranes have proteins with channels or pores that allow for the passage of hydrophilic molecules.
c. polar substances have an easier time passing directly through membranes than nonpolar substances do.
d. the current concept of a membrane can be best summarized by the fluid mosaic model.
E)
The lipid bilayer serves as a hydrophobic barrier between two fluid regions.
c. polar substances have an easier time passing directly through membranes than nonpolar substances do.
Which of the following would not affect diffusion?
a. molecular weight
b. concentration
c. color
d. temperature
c. color
In an enzyme-catalyzed reaction such as X + Y = Z, Z is the
Product
Intermediates are associated with which of the following?
a. antioxidants
b. dead cells
c. free energy
d. metabolic pathways
d. metabolic pathways
_______ reactions use energy to build complex molecules.
Anabolic
Which of the following binds to an allosteric site in order to change the shape of enzyme so that the substrate won’t bind to the active site?
a. cofactor
b. suppressor
c. activator
d. inhibitor
d. inhibitor
Typically, what molecule is causing feedback inhibition in a metabolic pathway?
The end product of the pathway
Enzymes increase the rate of reaction by lowering what kind of energy?
Activation
Essentially, the first law of thermodynamics says that
energy can neither be created nor destroyed
The second law of thermodynamics states that
energy tends to become increasingly disorganized
A reaction that releases free energy is known as a(n) _____ reaction.
exergonic
When a substrate binds to the active site of an enzyme, it changes the shape of the enzyme to help the reaction proceed. What is this model called?
induced fit
Plants need which of the following to directly carry out photosynthesis?
a. H2O
b. CO2
c. O2
d. lipid
e. both H2O AND CO2
e. both H2O and CO2
The final electron acceptor in aerobic respiration is
O2
Pyruvate is regarded as the end product of
glycolysis
Glycolysis typically takes place in the
cytoplasm
The oxygen released in photosynthesis comes from
water
Which of the following conditions is NOT required for Calvin Cycle?
a. carbon dioxide is present
b. the plant is exposed to light
c. RuBP is present
d. enough ATP
e. enough NADPH
b. the plant is exposed to light
The correct sequence of the three processes listed below is:
I – glycolysis II – oxidative phosphorylation III – citric acid cycle
I – III – II or glycolysis - citric acid cycle - oxidative phosphorylation
An organism that can produce its own food is called a(n)
autotroph
The citric acid cycle takes place in the
mitochondria
Four of the five answers listed below are catabolic processes for carbon compounds. Select the EXCEPTION.
a. Calvin cycle
b. citric acid cycle
c. fermentation
d. cellular respiration
e. glycolysis
Calvin cycle
Define biology
the study of life
Properties of life (8 characteristics that define life)
order, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing.
Order
consists of one or more cells
Positive response to stimuli
movement towards a stimulus
Negative response to stimuli
movement away from a stimulus
Reproduction in single-celled organisms
duplicate DNA and divide it equally, divides to form two new cells
Reproduction in multi-cellular organisms
produce specialized reproductive cells that form new individuals,genes containing DNA are passed to offspring
What is adaptation?
“fit” to the environment, consequence of evolution by natural selection
What do adaptations enhance of individuals exhibiting them?
reproductive potential
Are adaptations constant or do they vary?
adaptations vary
What do gene instructions direct?
cellular growth and development
Why do offspring exhibits characteristics of their parents?
From the DNA or genes that get passed on during reproduction
What is regulation as a property of life?
complex organisms requiring multiple regulatory mechanisms to coordinate internal functions
Example: circulatory system carries oxygen throughout the body, delivers nutrients to cells
What is homeostasis?
the ability of an organism to maintain constant internal conditions
What is energy processing as a property of life?
All organisms use a source of energy for their metabolic activities.
Example: plants capturing light energy from the Sung and converting it into chemical energy in food
What is the smallest and most fundamental unit of matter?
atom
What is an atom?
nucleus surrounded by electrons
What do atoms combine to form?
a molecule
What is a molecule?
chemical structure consisting of at least two atoms held together by a chemical bond
What are macromolecules?
large molecules formed by combining monomers, biologically important
Example: DNA
What are monomers?
molecules, smaller units
What are organelles?
small structures in cells that perform specialized functions
What is the smallest fundamental unit of structure and function in living organisms?
cell
Why aren’t viruses considered living?
they are not made of cells; they have to invade and hijack a living cell
What are prokaryotic cells?
single-celled organisms lacking organelles surrounded by a membrane and do not have nuclei surrounded by nuclear membranes
What are eukaryotes?
organisms with membrane-bound organelles and nuclei
What are organs?
collections of tissues grouped together based on a common function
Are organs found in:
a. plants only
b. plants and animals
c. animals only
b. plants and animals
What is an organ system?
functionally related organs
What are organisms?
individual living entities
What are microorganisms?
single-celled prokaryotes and single-celled eukaryotes
What is a basic unit of matter consisting of a dense central nucleus surrounded by a loud of negatively charged electrons?
atom
What is a molecule?
a phospholipid, composed of many atoms
What is an organelle?
structures that perform functions within a cell
Differentiate between organisms, populations, and communities
in a park, each person is an organism. together all the people make up a population. all the plant and animal species in the park compromise a community
Describe the levels of organization from smallest to largest
atom - molecule - organelles - cells - tissues - organs - organ systems - organisms - populations - communities - ecosystem - biosphere
Which of the following statements is false?
a. tissues exist within organs which exist within organ systems
b. communities exist within populations which exist within ecosystems
c. organelles exist within cells which exist within tissues
d. communities exist within ecosystems which exist in the biosphere
b. communities exist within populations which exist within ecosystems
What is applied science?
a form of science that solves real-world problems
what is basic science?
science that seeks to expand knowledge regardless of the short-term application of that knowledge
What is a control?
a part of an experiment that does not change during the experiment
What is deductive reasoning?
a form of logical thinking that uses a general statement to forecast specific results
What is descriptive science?
A form of science that aims to observe, explore and find things out
Define falsifiable
able to be disproven by experimental results
What is a population?
collectively, all the individuals of a species living within a specific area
What is a community?
set of populations inhabiting a particular area
What is an ecosystem?
all the living things in a particular area together with abiotic, or non-living, parts of that environment
What is the biosphere?
collection of all ecosystems, represents zones of life on earth include land, water and portions of he atmosphere
What is evolution?
the process of gradual change during with new species arise from older species
How many levels are in the current taxonomic system?
8 levels
What are the 8 levels of the current taxonomic system?
species, genus, family, order, class, phylum, kingdom, domain
What are the 3 domains of life?
Eukarya, Archae, and the Bacteria
What organisms are in the domain eukarya?
fungi, plants, animals, and protists
What are archae?
single-celled organisms without nuclei, includes many extremophiles living in harsh environments
What are bacteria?
single-celled organisms without nuclei
Are classifications permanent?
No, they will change when new information becomes available
What are bionomial names?
consists of genus name (capitalized) and the species name (lowercase)
What is a phylogenetic tree?
diagram showing evolutionary relationships among biological species based on similarities and differences in genetic or physical traits or both
What do the internal nodes of the phylogenetic tree represent?
represent ancestors and points of evolution when an ancestor diverged to form two new species
What does the length of the branch on a phylogenetic tree represent?
estimate of relative time
define neurobiology
study of the nervous system
define paleontology
study of life’s history by fossils
define zoology
study of animals
define botany
study of plants
define ecologist
specialist studying the interactions of organisms in their environments
define physiologists
specialist studying the workings of cells, tissues, and organs
define science
knowledge about the natural world
What is the scientific method?
method of research with defined steps that include experiments and careful observation
What is a hypothesis?
suggested explanation for an event, which can be tested
What is a scientific theory?
generally accepted, thoroughly tested and confirmed explanation for a set of observations or phenomena
What are scientific laws?
describe how elements of nature will behave under certain specific conditions
What are natural sciences?
fields of science related to the physical world and its phenomena and processes
What are life sciences?
study living things
What are physical sciences?
study non-living matter
What is inductive reasoning?
form of logical thinking that uses related observations to arrive at a general conclusion
What is qualitative data?
descriptive
What is quantitative data?
consisting of numbers
What is deductive reasoning?
form of logical thinking that uses a general principle or law to forecast specific results
What does descriptive science aim to do?
to observe, explore, and discover
Hypothesis-based science
begins with a specific question or problem and a potential answer or solution to be tested
What are the steps of the scientific methods?
make an observation, ask a question, form a hypothesis , make a prediction, do an experiment, analyze results, determine if data supports hypothesis, report results or try again
What is a variable?
any part of the experiment that can vary or change during the experiment
What is a control?
part of the experiment that does not change
Define soluble
dissolves in water
Define insoluble
does not dissolve in water
key building blocks of the chemicals found in living things
carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus
Matter
occupies space and has mass
What are elements?
substances that cannot be broken down or transformed chemically into other substances
Smallest component of an element that retains all of the chemical properties of that element
atom
All atoms contain protons, electrons, and neutrons except:
Hydrogen which only has one proton and one electron
What is a proton?
positively charged particle that resides in the nucleus
What is the nucleus?
the core of an atom
What is the mass and charge of a proton?
mass of 1 charge of +1
What is an electron?
negatively charged particle that travels in the space around the nucleus
What is the mass and charge of an electron?
no mass, charge of -1
What is a neutron?
reside in the nucleus on atom
What is the mass and charge of a neutron?
mass of 1, no charge
What is the mass of an atom equal to?
the number of protons and neutrons of that atom
What is the atomic number of an element?
equal to the number of protons that the element contains
What is the mass number?
number of protons plus the number of neutrons in that element
What is the periodic table of elements?
chart of elements including atomic number and relative atomic mass of each element
What are isotopes?
different forms of the same element with the same number of protons but different number of neutrons
What elements have naturally occurring elements
carbon, potassium and uranium
Most common isotope of carbon
Carbon-12
What are radioactive isotopes?
an isotope that spontaneously emits particles or energy to form a more stable element
What is the half-life of an isotope?
the time it takes for half of the original concentration of an isotope to decay to its more stable form
How many electrons can be hold in the closest shell
2 electrons
What shell is filled first with electrons?
the closest shell to the nucleus
How many electrons can the second shell hold?
8 electrons
How many electrons can the third shell hold?
8 electrons
How are electrons arranged in the 2nd and 3rd shells?
arranged in four pairs
How are electron shells filled?
one position in each pair is filled with an electron before any pairs are completed
What do the rows of the periodic table represent?
rows correspond to the number of shells that the elements within that row have
What do the columns of the periodic table represent?
Increasing numbers of electrons from left to right
When is an atom most stable?
When its outermost shell is full
What are chemical bonds?
interactions between two or more of the same or different elements that result in the formation of molecules
What is the octet rule?
states that the outermost shell of an element with a low atomic number can hold eight electrons
What can an element do to satisfy the octet rule?
donate, accept, or share electrons
what is an ion?
an atom or compound that does not contain equal number of protons and electrons, and therefore has a net charge
What are cations?
positive ions that are formed by losing electrons
What are anions?
negative ions that are formed by gaining electrons
What is an electron transfer?
movement of electrons from one element to another
Name 4 types of bonds
ionic, covalent, hydrogen bonds, and van der Waals interations.
Which bonds have strong interactions?
ionic and covalent bonds
What kind of charge will an element have if it accepts an electron?
negative charge
What is an ionic bond?
a chemical bond that forms between ions of opposite charges
What are covalent bonds?
a type of strong bond between two or more of the same or different elements; forms when electrons are shared between elements
Which bond(s) dissociate in water?
a. ionic bonds
b. covalent bonds
c. both
a. ionic bonds
What type of bonds are used to form water?
covalent bonds
What are the two types of covalent bonds?
polar and non-polar
What are non-polar covalent bonds?
bonds formed between two atoms of the same element or between different elements that share the electrons equally
What are polar covalent bonds?
a type of covalent bond in which electrons are pulled toward one atom and away from another, resulting in a slightly positive and slightly negative charged regions of the molecule
Does oxygen have a slightly positive or negative charge in water?
slightly negative because the electrons spend more time near the oxygen nucleus
Does hydrogen have a slightly positive or negative charge in water?
slightly positive charge because electrons spend more time near oxygen than hydrogen nuclei
What are two frequently occurring weak bonds?
hydrogen and van der Waals interactions
What is a hydrogen bond?
A weak bond between partially positively charged hydrogen atoms and partially negatively charged elements or molecules
What are van der Waals interactions?
a weak attraction or interaction between molecules caused by slightly positively charge or slightly negatively charged atoms
Where do van der Waals interactions occur?
between polar, covalently bound, atoms in different molecules
How does MRI imaging works?
by subjecting hydrogen nuclei to fluctuating magnetic fields which cause them to emit their own magnetic field
How much of the body is made up of water?
approx. 60-70%
Define hydrophilic
a substance that dissolves in water; water-loving
Define hydrophobic
a substance that does not dissolve in water; water-fearing
What is temperature?
a measure of the motion (kinetic energy) of molecules
Define evaporation
the release of water molecules from liquid water to form water vapor
Example of a solvent
water
What is a solvent?
a substance capable of dissolving another substance
What are spheres of hydration?
charged particles form hydrogen bonds with a surrounding layer of water molecules, also known as hydration shells
Why is water an effective solvent
due to its polarity
What is cohesion?
the intermolecular fores between water molecules caused by the polar nature of water, creates surface tension
What is surface tension?
the cohesive force at the surface of a body of liquid that prevents the molecules from seperating, capacity of a substance to withstand rupture when placed under tension or stress
What is adhesion?
the attraction between water molecules and other molecules
What is the pH of a solution?
a measure of its acidity or alkalinity
What is litmus paper?
paper treated with natural water-soluble dye so it can be used as a pH indicator
What does the pH test measure
the amount of hydrogen ions that exists in a given solution
high concentration = low pH
low concentration = high pH
What does a change of one unit on the pH scale represent
a change in the concentration of hydrogen ions by a factor of 10
What is the pH of pure water
neutral (7)
What pH levels are acidic?
anything below 7
What pH levels are alkaline?
anything above 7
What is the pH of blood?
7.4 slightly alkaline
What is the pH of the stomach?
1 - 2 highly acidic
What are acids?
substances that provide hydrogen ions (H+) and lower pH
What are bases?
substances that provide hydroxide ions (OH-) and raise pH
Window of the pH scale of cells in the body
7.2 - 7.6
What do buffers readily absorb?
excess H+ or OH-, this allows for the body to maintain pH levels
Buffer system of the human body
carbonic acid (H2CO3) and bicarbonate (HCO3-) anion
What are large molecules necessary for life that are built from smaller organic molecules?
biological macromolecules
What are the 4 major classes of biological macromolecules?
carbohydrates, lipids, proteins and nucleic acids
Are biological macromolecules organic or inorganic?
organic because they contain carbon
“foundation” element for molecules in living things
carbon
how many covalent bonds can carbon form
4
natural sources of carbohydrates
grains, fruits, and vegetables
what is the formula representing carbohydrates
(CH2O)n, where n = number of carbon atoms in the molecule
Define monosaccharides
simple sugars
Example: glucose
form of monosaccharides
exist as linear chain or as ring-shaped molecules
formula for glucose
C6H12O6
glucose, galactose, and fructose are all found in
carbohydrates
galactose and fructose are
a. monosaccharides
b. polysaccharides
c. disaccharides
a. monosaccharides
What are disaccharides?
form when two monosaccharides undergo a dehydration reaction
Lactose maltose and sucrose are
a. monosaccharieds
b. polysaccharides
c. disaccharides
c. disaccharides
Most common disaccharide
sucrose
What is a polysaccharide
a long chain of monosaccharides linked by covalent bonds
starch, glycogen, cellulose, and chitin are
a. monosaccharieds
b. polysaccharides
c. disaccharides
b. polysaccharides
What is starch
stored form of sugars in plants made up of amylose and amylopectin
What is glycogen?
storage form of glucose in humans and other vertebrates, made up of monomers of glucose
What is cellulose?
makes up cell walls of plants, abundant natural biopolymer
define dietary fiber
cellulose passing through our digestive system
What breaks down cellulose into glucose monomers
cellulase
What is chitin?
nitrogenous carbohydrate
Are lipids polar or non-polar molecules?
non-polar molecules
Where do cells store energy for long-term use
fats
What are fats, oils, waxes, phospholipids, and steroids?
Lipids
What does a fat molecule consist of?
two main components - glycerol and fatty acids
What are fatty acids composed of?
long chain of hydrocarbons to which an acidic carboxyl group is attached
How many fatty acids are in a triglyceride?
three
What are saturated fatty acids
fatty acids saturated with hydrogen; hydrogen atoms attached to the carbon skeleton is maximized
What are unsaturated fatty acids
fatty acids containing a double bond in the hydrocarbon chain
What are oils
unsaturated fats at room temperature
What is a monounsaturated fat
one double bond in the molecule
what is a polyunsaturated fat
more than one double bond in the molecule
How are saturated fats packed?
tightly, solid at room temperature
Are unsaturated or saturated fats better for you?
unsaturated fats because the improve blood cholesterol while saturated fats contribute to plaque formation in the arteries
What type of fats are made through artifical hydrogenation
trans-fats
What are essential fatty acids?
fatty acids required but not synthesized by the human body such as omega-3 fatty acids
What are omega-3 fatty acids important for in the body?
brain function and normal growth and development
What are phospholipids?
a major constituent of the membranes of cells; composed of two fatty acids and a phosphate group attached to the glycerol backbone
Which layer of the phospholipid faces the water?
phosphate group
which layer of the phospholipid faces away from the water?
the fatty acid side
What kind of structure do steroids have?
four, linked carbon rings - several with short tails
Are steroids hydrophilic or hydrophobic?
hydrophobic
Cholesterol is a
a. protein
b. steroid
c. lipid
d. carbohydrate
b. steroid
What is a protein?
a biological macromolecule composed of one or more chains of amino acids
How many different types of amino acids are there?
20
What are enzymes?
catalysts in biochemical reactions, usually proteins
Function of enzymes
to break molecular bonds, to rearrange bonds, or to form new bonds
What are hormones?
chemical signaling molecules, usually proteins or steroids, secreted by an endocrine gland or group of endocrine cells that act to control or regulate specific physiolgical processes
Define denaturation
the loss of shape in a protein as a result of changes in temperature, pH, or exposure to chemicals
What are amino acids
monomers that make up proteins
What is the composition of an amino acid
central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), and a hydrogen atom. + a variable R group
What is the difference in structure of different amino acids?
R group
What determines the chemical nature of an amino acid
R group
What kind of bonds do amino acids use to bond to one another?
peptide bonds
What is a polypeptide?
polymer of amino acids, long chain of amino acids linked by peptide bonds
When polypeptide or polypeptides have combined together, have a distinct shape, and have a function we refer to them as:
proteins
What are the 4 levels of protein structure
primary, secondary, tertiary and quaternary
What is the primary protein structure?
sequence of a chain of amino acids - determined by gene that encodes the protein
What is the secondary protein structure?
hydrogen bonding of the peptide backbone causes the amino acids to fold into a repeating pattern
Most common structures of secondary protein structures
alpha - helix, and beta - pleated
describe the structure of the alpha helix
bonds form between every fourth amino acid and cause a twist in the amino acid chain
describe the structure of the beta - pleated
pleats are formed by hydrogen bonding and align parallel to each other, and hydrogen bonds form between the same pairs of atoms on each of the aligned amino acids
What types of proteins are alpha-helix and beta-pleated commonly found in?
globular and fibrous proteins
What is the tertiary protein structure?
three-dimensional folding pattern of a protein due to side chain interactions
What is the quaternary protein structure?
protein consisting of more than one amino acid chain
What are the 2 main types of nucleic acids?
DNA & RNA
What monomers make up DNA and RNA?
nucleotides
What is a nucleotide composed of?
nitrogenous base, a pentose (five-carbon) sugar, and a phosphate group
What is the structure of DNA
two strands of nucleotides in a double-helical structure
Where are the nitrogenous bases of DNA stacked?
in the interior of the structure
In DNA, what lies on the outside of each strand?
alternating sugar and phosphate groups
What kind of bonds are used in DNA base pairing
hydrogen bonds
The smallest unit of a living thing is a
cell
Bacteria and archae cells are classified as
prokarytic
What cells are classified as eukaryotic
animal, plant, fungal, and protist
What is a microscope?
instrument that magnifies an object
Microscope part that changes the orientation of the image
Example: specimen that is right-side up and facing right on the microscope will appear upside-down and facing left
optics of the lenses of a light microscope
How does a light microscope work?
Visible light passes through and is bent by the lens system allowing the user to see the specimen
What is an advantage of using a light microscope?
advantageous for viewing living organisms, however stains must be used to distinguish cell components
Define magnification
degree of enlargement of an object
What is resolving power?
the ability of a microscope to allow the eye to distinguish two adjacent structures as seperate
What microscope has a lower magnification than light microscopes and provides a three-dimensional view of a specimen?
Dissection microscope
Dissecting microscopes are designed to give a
magnified and clear view of tissue structure as well as the anatomy of the whole organism
Define binocular
two separate lens systems
Does the orientation change the view of the specimen in a dissecting microscope?
No, the optics correct the image to appear as if being seen by the naked eye
Instead of a beam light, this microscope uses a beam of electrons
electron microscope
A disadvantage of an electron microscope is that
living cells cannot be viewed
In the electron microscope, the electron beam moves best in a
vacuum
In a scanning electron microscope, how does the beam of electrons move?
back and forth across a cell’s surface, showing the details of cell surface characteristics by reflection
What microscope provides details of a cell’s internal structures?
transmission electron microscope
What are cytotechnologists?
professionals who study cells through microscopic examinations and other laboratory tests
What does the unified cell theory state?
all living things are composed of one or more cells, that the cell is the basic unit of life, and that all new cells arise from existing cells
Name the four components all cells share
plasma membrane, cytoplasm, DNA, ribosomes
What is the plasma membrane?
outer covering that separates the cell’s interior from its surrounding environment
What is the cytoplasm?
jelly-like region within the cell where other cellular components are found
What is DNA?
genetic material of the cell
What are ribosomes?
particles that synthesize proteins
What is a prokaryotic cell?
unicellular organism that lacks a nucleus, or any other membrane-bound organelle
Where is DNA found in prokaryotic cells?
in the central part of the cell in the nucleoid
What is the nucleoid?
A darkened region in the central part of the prokaryotic cell
What is the cell wall of bacteria composed of?
peptidodoglycan
Why is bacteria different from Archae and eukaryotes?
cell wall made of peptidoglycan, compromised of sugars and amino acids, and many have a polysaccharide capsule
Functions of the cell wall
extra layer of protection, helps the cell maintain its shape, and prevents dehydration
Function of capsule
enables the cell to attach to surfaces in its environment
What is a eukaryotic cell?
a cell that has membrane-bound nucleus and other membrane-bound organelles that have specialized functions
What is an organelle?
a compartment or sac in the cell that have specialized functions
Are prokaryotic or eukaryotic cells bigger?
Eukaryotic cells are significantly bigger
As the cell becomes ________, it becomes more difficult for the cell to aquire sufficient materials to support the processes inside the cell.
larger
A plasma membrane is composed of
a phospholipid bilayer with embedded proteins that separate internal contents of the cell from its surrounding environment
What are microvilli?
tiny hair-like folds in the plasma membrane
What increases surface area of plasma membrane?
microvilli
Where are microvilli typically found in the human body?
lining the small intestine
Describe celiac disease
immune response to gluten that damages microvilli - afflicted individuals cannot absorb nutrients leads to malnutrition cramping diarrhea
the consistency of cytoplasm
semi-solid
What is cytosol
the gel-like material of the cytoplasm in which cell structures are suspended
What is the cystoskeleton of a cell
the network of protein fibers
Function of the cytoskeleton
maintains cell shape, secures organelles in specific positions, allows movement within the cell and enables unicellular organisms to move
Name the 3 types of fibers within the cytoskeleton:
microfilaments (actin filaments), intermediate filaments, and microtubules
Microfilaments are often found in
muscle cells
Keratin is an example of a(n)
intermediate filament
Are microfilaments thick or thin?
thin
Are microtubules thick or thin?
thick
Function of microtubules
guide organelle movement
What do microtubules do during cell division
pull chromosomes to their poles
What are the structural components of flagella and cilia?
microtubules
What functions as a microtubule-organizing center?
the centrosome
What role do centrioles play in cell division?
they pull duplicated chromosomes to opposite ends of the dividing cell
What is the flagella?
long, hair-like structures that extend from the plasma membrane
Function of flagella
move the entire cell
When present where are cilia located?
they extend along the entire surface of the plasma membrane
What are cilia?
short, hair-like structures that are used to move entire cells or move substances alon gthe outer surface of the cell
What is the endomembrane system composed of?
nuclear envelope, lysosomes, and vesicles, the endoplasmic reticulum and Golgi apparatus, and the plasma membrane (although it isn’t in the cell) because it interacts with these organelles
The nucleus houses the cell’s DNA in the form of
chromatin
What does the DNA do in the cell?
Directs the synthesis of ribosomes and proteins
What is the nuclear envelope?
a double-membrane structure that constitutes the outermost portion of the nucleus
What are the inner and outer membranes of the nuclear envelope composed of?
phospholipid bilayers
What is the purpose of the pores punctuated in the nuclear envelope?
controls the passage of ions, molecules, and RNA between the nucleoplasm and the cytoplasm
What are chromosomes composed of?
chromatin
What does DNA and proteins form
chromatin
How many chromosomes are in the human body?
46
What is the nucleolus?
the darkly staining body within the nucleus that is responsible for assembling ribosomal subunits
Function of the nucleolus
aggregates the ribosomal RNA with associated proteins in order to assemble the ribosomal subunits that are then transported through the nuclear pores into the cytoplasm
What is the endoplasmic reticulum (ER)?
series of interconnected membranous tubules
Function of ER
modifies proteins and synthesizes lipids
What is the lumen or cisternal space?
the hollow portion of the ER tubules
What is on the surface of the RER?
ribosomes
What does the RER do?
makes phospholipids for cell membranes, modifies proteins
RER is abundant in cells that secrete:
proteins, such as the liver
Function of smooth endoplasmic reticulum
synthesis of carbohydrates, lipids, and steroid hormones; detoxification of medications and poisons; alcohol metabolism; and storage of calcium ions
Function of the golgi apparatus
sorts, packages, tags, and distributes lipids or proteins
What is the golgi apparatus?
a series of flattened membranous sacs
What do transport vesicles do with lipids or proteins?
deposit their contents into other parts of the cell where they will be used
What do secretory vesicles do?
Fuse with plasma membrane and release their contents outside of the cell
What type of cells have an abundant number of golgi?
cells that engage in a great deal of secretory activity
What additional role does the golgi play in plant cells?
role of synthesizing polysaccharides
What part of the cell is known as the “garbage disposal”?
Lysosome
What is a lysosome?
an organelle in an animal cell that functions as the cell’s digestive component
What does the lysosome break down?
proteins, polysaccharides, lipids, nucleic acids, and worn-out organelles
What is phagocytosis?
a section of the plasma membrane of the macrophage invaginates (folds in) and engulfs a pathogen
What are vesicles and vacuoles?
membrane-bound sacs that function in storage and transport
What is the difference between vesicles and vacuoles?
vacuoles are somewhat larger, and the membrane of a vacuole does not fuse with the membranes of other cellular components
What are ribosomes?
cellular structures responsible for protein synthesis
Where are ribosomes abundant?
in immature red blood cells
What is the mitochondria?
an oval-shaped, double-membrane organelles that is the “powerhouses” of a cell responsible for making ATP
What is cellular respiration?
the formation of ATP from the breakdown of glucose
Why are mitchondria different from other organelles?
they have their own ribosomes and DNA
What are cristae
inwardly projecting folds of the inner membrane of the mitochondria
What is the mitochondrial matrix?
area surrounded by the cristae or inner foldings of the mitochondria
What cells have a very high concentration of mitochondria?
muscle cells because they need a lot of energy to contract
What are peroxisomes?
small, round organelles enclosed by single membrances
Function of peroxisomes
carry out oxidation reactions to break down fatty acids and amino acids, detoxify poisons - example: alcohol
What organelles are found in animals cells that are not seen in plants?
centrioles, centrosomes, and lysosomes
What are some structure that plant cells have that animal cells do not?
cell wall, chloroplasts, plasmodesmata, and plastids used for storage, and a large central vacuole
What is a cell wall?
rigid covering external to the plasma membrane
Function of the cell wall
protects the cell, provides structural support, gives shape to cell
What cells have cell walls?
plants, fungal, protists
What is a plant’s cell wall composed of?
cellulose
What is cellulose?
a polysaccharide made up of long, straight chains of glucose units
Why are chloroplasts different from other organelles?
they have their own DNA and ribosomes
define autotrophs
organism able to make their own food
define heterotrophs
rely on other organisms for food
What are thylakoids?
interconnected, stacked fluid-filled membrane sacs
What is a granum (grana - plural) ?
a stack of thylakoids
What is the stroma?
fluid enclosed by the inner membrane and surrounding the grana
What is chlorophyll?
green pigment found in chloroplasts
What is the function of chlorophyll?
captures the energy of sunlight for photosynthesis
What is the role of the central vacuole?
regulates the cell’s concentration of water in changing environmental conditions, stores proteins in developing seed cells
Define turgor pressure
outward pressure caused by the fluid inside the cell
What is the extracellular matrix?
glycoproteins and protein collagen
Function of the extracellular matrix
holds the cells together to form a tissue, allows the cells within the tissue to communicate with each other
example: blood clotting
What are intercellular junctions?
direct contact made by cells to communicate
What are junctions between plant cells?
plasmodesmata
What are junctions between animal cells
tight and gap junctions, and desmosomes
What are plasmodesmata?
numerous channels that pass between the cell walls of adjacent plant cells, connecting their cytoplasm and enabling signal molecules and nutrients to be transported from cell to cell
What is a tight junction?
a watertight seal between two adjacent animal cells
What holds the cells tightly against each other in a tight junction
proteins
What does a tight junction prevent?
leaking of materials between cells
What do desmosomes do?
join two animal cells together by acting like spot welds between adjacent epithelial cells; sheet-like formation in organs and tissues such as the skin, heart, and muscles
What are gap junctions?
in animal cells, they are channels between adjacent cells that allow for the transport of ions, nutrients, and other substances that enable cells to communicate
Are plasma membranes dynamic?
No they are dynamic and constantly in flux
The plasma membrane carriers markers that:
allow cells to recognize one another
The plasma membrane carriers receptors that:
are attachment sites for specific substances that interact with the cell
What does the fluid mosaic model describe?
the structure of the plasma membrane in which components (phospholipids, cholesterol, proteins and carbohydrates) are able to flow and change position, while maintaining the basic integrity of the membrane
The interior of the plasma membrane is _______, while the outside surfaces are _______.
hydrophobic, hydrophilic
What are integral proteins?
proteins of the plasma membrane serving as channels or pumps to move materials into or out of the cell
What is a glycoprotein?
protein with carbohydrate attached
What is a glycolipid?
lipid with carbohydrate attached
define selectively permeable
characteristic of a membrane that allowing some substances through but not others
what is passive transport
method of transporting material that does not require cell energy
what is a concentration gradient
an area of high concentration across from an area of low concentration
What is diffusion?
passive process of transport of low-molecular weight material down its concentration gradient
What factors affect diffusion?
concentration of gradient, mass of the molecules diffusing, temperature, and solvent density
What is facilitated transport?
a process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins
What is osmosis?
the transport of water through a semipermeable membrane from an area of high water concentration to an area of low water concentration across a membrane
Why is osmosis different from other passive transports?
it only transports water
What does tonicity describe?
the amount of solute in a solution
What is osmolarity?
the measure of the tonicity of a solution
terms used to relate the osmolarity of a cell to the osmolarity of the extracellular fluid that contains the cells
hypertonic, hypotonic, and isotonic
What does hypertonic describe?
describes a solution in which exracellular fluid has higher osmolarity than the fluid inside the cell
What does hypotonic describe?
describes a solution in which extracellular fluid has lower osmolarity than the fluid inside the cell
What does isotonic describe?
describes a solution in which the extracellular fluid has the same osmolarity as the fluid inside the cell
What does a cell do in hypertonic solution?
the cell will shrink
What does a cell do in a hypotonic solution?
the cell will burst
What does a cell do in an isotonic solution?
stays the same because solution comes in and out of the cell at the same rate
What is active transport?
the method of transporting that requires energy
What is an electrochemical gradient?
a gradient produced by the combined forces of the electrical gradient and the chemical gradient
Describe primary active transport
uses ATP to move a substance into the cell and a second substance is moved out of the cell
Describe secondary active transport
movement of material using the energy of the electrochemical gradient established by primary active transport
What is endocytosis?
a type of active transport that moves substances, including fluids and particles, into a cell
Common characteristic of endocystosis variations
The plasma membrane of the cell invaginates, forming a pocket around the target particle. The pocket pinches off, resulting in the particle being contained in a newly created vacuole that is formed from the plasma membrane
What is phagocytosis?
a process that take macromolecules that the cell needs from the extracellular fluid; a variation of endocytosis
What is pinocytosis?
a process that takes solutes that the cell needs from the extracellular fluid: a variation of endocytosis
What is receptor-mediated endocytosis?
a varient of endocytosis that involves the use of specific binding proteins in the plasma membrane for specific molecules or particles
What is exocytosis?
a process of passing material out of a cell
What are bioenergetics?
the concept of energy flow through living systems
What is metabolism?
all the chemical reactions that take place inside cells, including those that use energy and those that release energy
Define anabolic
describes the pathway that requires a net energy input to synthesize complex molecules from simpler ones
Define catabolic
describes the pathway in which complex molecules are broken down into simpler ones, yielding energy as an additional product of the reaction
What is thermodynamics
the study of energy and energy transfer involving physical matter
In an open system,
energy can be exhanged with its surroundings
In a closed system,
energy cannot be exchanged with its surroundings
The laws of thermodynamics describe
the transfer of energy in and among all systems in the universe
What does the second law of thermodynamics state?
energy will always be lost as heat in energy transfers or transformations
What is heat energy?
the energy transferred from one system to another that is not work
What is entropy?
the measure of randomness or disorder within a system
What does high entropy mean?
high disorder, low energy
What is kinetic energy?
energy associated with objects in motion
What is potential energy?
energy with potential to do work
What is chemical energy?
potential energy that was in chemical bonds that were broken and released chemical energy
What is exergonic reactions?
describes a chemical reaction that results in products with less chemical potential energy than the reactants, plus the release of free energy
What is an endergonic reactions?
describes a chemical reaction that results in products that store more chemical potential energy than the reactants
What is activation energy?
amount of initial energy necessary for reactions to occur
What is an enzyme?
a molecule that catalyzes a biochemical reaction
What is a substrate?
a molecule on which the enzyme acts
What is the active site?
a specific region on the enzyme where the substrate binds
What is competitive inhibition?
general mechanism of enzyme activity regulation in which a molecule other than the enzyme’s substrate is able to bind the active site and prevent the substrate itself from binding, thus inhibiting the overall rate of reaction for the enzyme (inhibitor competes with substrate for binding to active site)
What is non-competitive inhibition?
an inhibitor molecule binds to the enzyme in a location other than the allosteric site but still blocks substrate binding to the active site
What is allosteric inhibition?
mechanism of inhibiting enzyme action where regulatory molecule binds to a second site and initiates a conformation change in the aactive site, preventing binding with the substrate
What is feedback inhibition?
use of a reaction product to regulate its own further production, product inhibits an enzyme for an earlier step in the reaction series
What does feedback inhibition control?
production of both amino acids and nucleotides
What is glycolysis?
the process of breaking glucose into two three-carbon molecules with the production of ATP and NADH
Where does glycolysis take place in the cell?
cytoplasm
Describe the process of glycolysis
starts with a six-carbon, ring-shaped structure of a glucose molecule
energy is used to evenly split the six-carbon sugar into two three-carbon pyruvate molecules
ATP and NADH are produces
What is acetyl CoA
combination of an acetyl group derived from pyruvic acid and coenzyme A which is made from pantothenic acid (a B-group vitamin)
Where does the citric acid cycle take place?
in the mitochondria
What is the citric acid cycle?
a series of enzyme-catalyzed chemical reactions of central importance in all living cells that harvests the energy in carbon-carbon bonds of sugar molecules to generate ATP; the citric acid cycle is an aerobic metabolic pathways because it requires oxygen in later reactions to process