CLEP Biology Chapter 3: Cellular and Molecular Biology

Aerobic Respiration

(In the presence of oxygen) - Begins with Glycolysis and proceeds through Krebs Cycle and Electron transport chain

Cell Theory

1. All living cells made up of 1+ cells 2. Cells are the basic units of life 3. All cells come from pre-existing cells

How much ATP can anaerobic respiration produce per glucose molecule

2 ATP molecules per glucose molecule

Uses energy generated from ATP to transport substances across membrane

Active transport

Is Glycolysis an aerobic or anaerobic reaction?

Anaerobic - requires no oxygen

Nucleus

Contains chromosomes

Grana

Disk like plates embedded in stroma of chloroplast which are the site of photosynthetic reactions

Division

Distributes remaining set of chromosomes in a mitosis like process

Anaerobic Reactions

Do not require oxygen

Krebs Cycle liberates what?

Electrons

Trait

Function of one protein of function of a group of proteins

Inorganic Cofactor

Include metal ions

tRNA

Link between the "language" of nucleotides (codon and anticodon) and the "language" of amino acids; chain of 80 nucleotides. At one point along chain, there are 3 unattached bases called anticodon which line up with corresponding codon during translation. Each tRNA has an attached specific amino acid

Smooth ER (SER)

Network of membraneous channels - does not have attached ribosomes - responsible for processing fats, lipids, and steroids, which are then packaged by Golgi Apparatus

Anaerobic Pathways

No oxygen present - This is also called fermentation. It breaks down the pyruvic acid molecules (3 carbons each) into end products. This is not as efficient as aerobic respiration and uses only small part of energy available in glucose molecules

Telophase

Nuclear membranes form around chromosomes and chromosomes disperse through new nucleoplasm and are no longer visible as chromosomes. Spindle fibers disappear. Then, cytokinesis

Calvin Cycle

Occurs in stroma of chloroplast; does not require light but does require use of products of photolysis (hydrogen and photolysis); the 6 CO2 molecules are linked with hydrogen forming glucose which can be linked to form polysaccharides which are then stored the cell

Homolog

Paired chromosomes of similar shape and size

Diffusion

Passive transport - molecules and ions flow through the cell membrane from an area of higher concentration to an area of lower concentration "moving down the gradient" - this is generally the means of transport for ions and molecules that can slip between the lipid molecules of the membrane - requires no added energy to propel substances through membrane

Organic Cofactors (Coenzymes)

Some coenzymes are not made by cells but must be obtained in the diet (ex: vitamins)

Cofactor

Some enzymatics require non-protein substance called a cofactor. The cofactor binds to the active site which allows substrate to fit into the active site

Metaphase

Spindle fibers pull chromosomes into alignment along metaphase plate of cell - ensures that one copy of each chromosome is distributed into each daughter cell

Animal Cell Contains

cell membrane, microvilli, cytoskeleton, ribosomes, endoplasmic reticulum, Golgi apparatus, secretory vesicles, lysosomes, mitochondria, nucleus

Robert Hooke

first to use term cells (looked at cork under microscope)

Gene

length of DNA that encodes for a particular protein. Each protein performs a specific functionnn in the cell

Antonie Van Leeuwenhoek

observed bacteria cells with microscopes and called them animalcules

4 Phases of Mitosis

prophase, metaphase, anaphase, telophase

Chromatid

2 indentical strands of chromatin

How much ATP can the ETC produce durign Aerobic respiration

32 molecules per glucose molecule

DNA replication

A portion of DNA unwinds separating 2 halves of double-helix aided by enzyme helicase. Another enzyme, DNA polymerase, binds to each strand and moves along them as it connects nucleotides using the DNA strands as templates. The new strand is complementary and forms new double-helix with a parent strand (which yields 2 identical double helix molecules of DNA)

Reduction

Affects the ploidy (referrinng to haploid or diploid) level, reducing it from diploid to haploid. 1. Chromosome replicate occurs before prophase then during prophase 2. Homologous chromosomes pair up and join at synapse, forming a tetrad (4 stranded structure composed of 4 chromatids). Sometimes, crossing over occurs in which some portions of chromatid break off and attach to another chromatid which results in wider array of genetic possibilities. Nuclear membrane disappears during late prophase. Each chromosome develops a kinetochore and as the spindle fibers attach to a chromosome, they move. 3. Metaphase: 2 chromosomes align themselves along metaphase plate. The chromosomes randomly sort. The resulting cells from meotic division will have mix of parent chromosomes 4. Anaphase - chromosome from each pair moves to separate end of cell 5. Telophase - Nuclear envelope may form. Cell divides in and 2 daughter cells are made. The nuclear envelopes dissolve. 6. Spindle fibers form again. All else proceeds through mitosis through metaphase, 7. anaphase, and 8. telophase 9. Each chromosome splits into 2 chromatids. 10. Cytokinesis forming 4 distinct gamete cells

Cell Membrane

All cells enclosed by cell membrane) or plasma membrane; separates cell from environment; composed of bilayer of phospholipids; sometimes endocytic vesicles

Inhibitor

Attach to enzymes active site and disallows cellular reaction to take place

Attached Ribosomes

Attached to the ER - Proteins made at the site of attached ribosomes are destined for use within the membrane-bound organelles

Cytoplasm

Between nucleus & cell membrane, cell filled with cytoplasm

Stroma

Body of chloroplast

Nuclear membrane

Boundary between nucleus and cytoplasm; double membrane which allows for entrance and exit of certain molecules through nuclear pores

Glycolysis

Breakdown of glucose into smaller carbon-containing molecules; yields ATP; It is the first step in all respiration pathways and occurs in the cytoplasm of all living cells. Each molecule of glucose (6 carbons) is broken down into 2 molecules of pyruvic acid and with 3 carbons each, 2 ATP, and 2 hydrogen atoms (attached to NADH - nicotinamide adenine dinucleotide);

Mitosis

Cell distibutes duplicated chromosomes so each daughter has full set of chromosomes and nucleus divides. One chromosome in each daughter call is from each parent. Mitosis has 4 phases. Only eukaryotic unicellular organisms reproduce by mitosis.

Cell cycle

Cell division that leads to 2 cells: interphase & mitosis, cytokineses.

Interphase

Cell is active in function. Cell growth and function occur at all phases: -During G1 phase, metabolism and protein synthesis are occuring at high rate and cell is growing. -During S phase, cell prepares for cell division by replicating DNA and proteins necessary to form new chromosomes -During G2 phase, more proteins are produced and the centrioles are replicated as well

Mitochondria

Centers of cellular respiration; more numerous in cells requiring more energy; self-replicating and contain own RNA and DNA and ribosomes; have a double-membrane

Light Reactions (photolysis)

Chlorophyll absorbs photon of light, which leaves chlorophyll in higher energy state; decomposition reaction that separates water molecules into hydrogen ions, oxygen ions, and high energy electrons. The oxygen atoms combine to form 02 and are released. The free hydrogens are grabbed by a molecule (called hydrogen acceptor) until needed. The chlorophyll supplies energy to series of reactions that produce ATP and ADP and inorganiz phosphate

Anaphase

Chromatids are separated from each other when the centromere divides. Each is then called a chromosome and they move along spindle fibers to opposite ends of cell

Prophase

Chromatin condenses into chromosomes within nucleus. Centrioles move to opposite ends of cell and spindle fibers extend from each centriole toward center of cell. Nucleolus is no longer visible but chromosomes are. Nuclear membrane dissolves and the spindle fibers attach to centromeres, forming kinetochore. Chromosomes are pulled to center by attached spindle fibers

Regulatory genes

Code proteins that determine functional or physiological events such as growth. They regulate when other genes start or stop encoding proteins which produces specific traits

Eukaryotic Cells

Contain membrane-bound intracellular organelles; plant, fungi. animal cells, protozia all have them; have nucleus; DNA organized into chromosomes

Restriction Enzymes

Cut sections of DNA molecules by cleaving at the sugar-phosphate backbone at a particular nucleotide sequence. They are made up of bacteria and act to destroy foreign DNA that has entered bacterial cel.

Chromatin

DNA + histones

Allele

Different forms of corresponding genes

Mode of transportation of molecule through cell membrane in which molecule can easily pass through lipid molecules of membrane

Diffusion

Facilitated Diffusion

Does not require added energy and cannot occur without help of specialized proteins. These proteins provide channels for specific molecules or ions to travel by through the membrane. This allows diffusion of molecules that cannot otherwise pass through the phospholipid bylayer

Microfilaments

Double-stranded chains of proteins that serve to give structure to cell. Together wih microtubules, they form the cytoskeleton, providing stability and structure

Krebs Cycle

During Aerobic respiration, Krebs cycle occurs after glycolysis in the matrix of a cell's mitochondria and breaks down pyruvic acid molecules (3 carbons each) into CO2, H+ protons and 2 ATP molecules. This also liberated electrons which enter next step

Electron Transport Chain

During Aerobic respiration, following glycolyis and Krebs cycle, ETC captures the energy released in Krebs cycle. The ETC is a series of cytochromes on the cristae in the mitochondria. The heme groups may either be oxidized (lose electron to form Fe3+) or reduced (gains electron to form Fe2+) as electrons are passed along ETC. As they pass from one cytochrome to another, energy is released (some lost as heat and the rest is stored in molecule of ATP). The final step: last electron carrier transfers 2 electrons to an oxygen atom that simultaneously combines with 2 protons from the surrounding medium to produce water.

Structural genes

Encode proteins that form organs and structural characteristics

ATP (Adenosine triphosphate)

Energy currency of cellular activity. In order for energy within cells to be released within small packets usable to cell (too big would destroy), large molecules need to be broken down in steps. ATP is a molecule that stores energy. It consists of a nitrogeneous base (adenine), a simple sugar (ribose), and three phosphate groups. When a cellular process requires energy, a molecule of ATP can be broken down into ADP (adenosine diphosphate plus a phosphate group) or AMP (adenosine monophospate plus 2 phosphate groups). Coupling this with energy-absorbing reactions allows cell to carry out functions

Regulation

Enzyme control may occur when the product of a reaction is also an inhibitor of the reaction which slows down production rate as the concentration of the product increases. Others may serve as a regulator by changing the structure of the active site making the enzyme more or less effective

Mode of transportation of molecule through cell membrane in which molecule can NOT easily pass through lipid molecules of membrane

Facilitated Diffusion

Free Ribosomes

Float unattached within cytoplasm; synthesizing by free ribosomes are made for use in the cytoplasm, not within membrane-bound organelles

Endocytic Vesicles

Form when cell encloses a particle outside of cell and pinches off to release it into cytoplasm.

Transcription

Formation of RNA which corresponds to a gene; DNA unzips and RNA nucleotides strung together to match DNA sequence by enzyme RNA polymerase. This new RNA (mRNA) migrates from nucleus to cytoplasm (is modified in process called post-transcriptional processing). In the processed RNA, each unit of 3 nucleotides or Codon encodes a particular amino acid

Chloroplasts

Found in plant cells; site of photosynthesis; chlorrophyll pigment molecules give chloroplast green color; stroma (or body of chloroplast) contains embedded disk like plates called grana which are the site of photosynthetic reactions

Genome mapping

Fragments of DNA to be assigned to specific chromosomems - maps are created for specific species based on results of studies of the genetic material found within that species

Plant Cell Contents

Golgi Apparatus, mitochondria, rough ER, ribosome, nucleus, nucleolus, smooth ER, cell walls, chloroplasts, central vacuole

Chlorophyll

Green pigment that absorbs a photon of light that allows photosynthesis to occur; located in grana of the chloroplast, must be present for photosynthesis to occur but is not consumed in process

Rough ER (RER)

Has attached ribosomes; in addition to packaging and transporting materials within the cell, the RER is instrumental to protein synthesis

Prokaryotic Cells

Have no nucleus or membrane-bound structures; DNA forms single chromosome which floats within cytoplasm; unicellular; include bacteria

Binary Fission

How bacteria (which lack nucleus) reproduce

Cytokinesis in animal cells

In animal cells, ring made up of protein actin surrounds center of cell and contracts. As actin ring contracts, pinches cytoplasm in 2 separate compartments. Each cell's plasma membrane seals, making 2 daughter cells

Difference between anaphase of mitosis and meiosis

In mieosis, one chromosome from each pair moves to separate end of cell. In mitosis, one of each chromosome pair (rather than one chromatid) separates.

Cytokinesis in plant cells

In plant cells, a cell plate forms across center of cell and extends towards edges of cell. Call wall forms on either side of the plate and original cell splits in two

Post-transcriptural processing

In transcription, prepares mRNA for protein synthesis by removing the non-coding sequences

Cellular Metabolism

Includes all types of energy transformation processes

Heme

Iron containing group

Endocytosis

Large molecules are taken up into a pocket of a membrane, pocket pinched off and molecules delivered into the cytoplasm (used by white blood cells to engulf bacteria)

Endoplasmic Reticulum

Large organization of folded membranes responsible for delivery of lipids and proteins to certain areas within the cytoplasm

Cytochromes

Located on the cristae of the mitochondria - site of ETC - pigment molecules which include a protein and a heme (iron containing group).

Structure of Chromosomes

Long chains of subunits called nucleosomes composed of short length of DNA wrapped around core of small proteins called histones. This is called a chromatin. This is tightly packed and coiled.

Central Vacuole

Membrane-bound fluid filled space which stores water and soluble nutrients for plant's use; tendency to absorb water provides for rigid shape of plant cells

Lysosomes

Membrane-bound organelles containing digestive enzymes; break down unused material within the cell, damaged organelles, or materials absorbed by the cell for use

Mutation

Mistake - common in DNA replication to have mutations - can happen from errors or damage/exposure; cells have built in mechanisms for finding/fixing these; if not found, expresses itself in small changes in cell structure and fuction.

Endosymbiont Hypothesis

Mitochondria are thought to be evolved from primitive bacteria that lived in a symbiotic relationship wth eukaryotic cells more than 2 billion years ago; plausible explanation of how mitochondria (which have many necessary components for life on their own) became an integral part of eukaryotic cells

Cell division

Mitosis - centers 0n replication and separation of strands of DNA. In a cell that is ready to divide, each strand of chromatin is duplicated. 2 identical strands called Chromatids remain attached at a point called centromere. During cell division, chromtin strands become more tightly coiled and packed forming a chromosome, which consists of 2 identical chromatids attached at centromere (X shape). Within nucleus, each chromosome pairs with another, called homologs. Each set is similar genetic constitution, but aren't identical.

Secretory Vesicles

Packets of material packaged by either the Gogli apparatus or the endoplasmic reticulum. The carry substances produced within the cell to the cell membrane. The vesicle membrane fuses with the cell membrane in a process called exocytosis, allowing the substance to leave the cell

Microtubules

Part of cytoskeleton - long hollow cylindrical protein tubules which give structure "loose skeleton", sometimes at base of flagella and give ability to move

Plant Cell differences

Plant cells have central vacuole and cell wall, organelles called chloroplasts for photosynthesis

Cell Walls

Plants only; Made up of cellulose and lignin making them strong and rigid; encloses the cell membrane providing strength and protection; store water under high concentration; provides support for organism; allows substances to pass through easily so transport is regulated by cell membrane

Nuclear Pores

Points at which the double nuclear membrane fuses together forming a passageway between the inside the nucleus and the cytoplasm outside the nucleus. They allow the cell to selectively move molecules in and out of the nucleus

Catabolism

Process of breaking down molecules and releasing stored energy

Anabolism

Process whereby cells build molecules and store energy

Cytokinesis

Produces 2 separate cells.

Meiosis

Producing 4 daughter cells each with a haploid set of unduplicated chromosomes (gametes). The parent cell is diploid (has normal set of paired chromosomes). Goes through 2 stage process; each cell has half the chromosomes of the parent. When 2 haploid cells fuse during fertilization, the resultant cell has one chromosome set from each parent and is diploid.

Microvilli

Projections of cell expending fro mcell membrane - increase surface level of cell membrane which increases area available to absorb nutrients; also contain enzymes involved in digesting certain types of nutrients

Properties of Enzymes

Protein molecules that act as catalysts for organic reactions - lowers the activation energy of a reaction and is not consumed in reaction - don't make things possible that wouldn't occur but speed them up; synthesized at ribosomes; An enzyme can bind 2 substrates and catalyze the formation of a new chemical bond linking the substrates. It can also bind a single substrate and catalyze the breaking of a chemical bond, releasing 2 products. Once the reaction has taken place, the unchanged enzyme is released - enzymes lower the activation energy needed to initiate cellular reactions

Cytoskeleton

Provides structural support to cell; Contains microtubules, microfilaments, and centrioles

Photosynthesis

Reactions that convert light energy into chemical energy (Carbon dioxide plus water => glucose plus oxygen) 2 Phases: light reactions & Calvin Cycle

Stages of Meiosis

Reduction & Division

Aerobic Reactions

Require oxygen

Cellular Respiration

Respiration occurs in all cells and breaks down molecules and releases energy for use by the cell.

Exocytosis

Reverse of endocytosis - exporting substances from cell

Nucleolus

Rounded area within nucleus of the cell where ribosomal RNA is synthesized. This is incorporated into ribosomes after exiting nucleolus

Prosthetic groups

Similar to cofactors - they also facilitate enzyme reactions but are bound to enzyme rather than being separate atoms or molecules

Cytoplasmic Organelles

Since all organelles outside nucleus but within membrane exist cytoplasm, they are called cytoplasmic organelles

Ribosomes

Site of protein synthesis within cell; composed of certain protein molecules and RNA

Viruses

Smaller than smallest cells; scientists don't agree whether they are alive; do not have ability to conduct metabolic processes on own; structure includes protein capsule, DNA or RNA, and sometimes enzymes; survive and replicate by invading a living cell

Cell

Smallest and most basic unit of living things; size and shape varies greatly

Osmosis

Special process of diffusino occuring only in water molecules - does not need added energy but occurs when water concentration inside cell differs from concentration outside cell - water moves out until equalized on both sides - aka isomotic

Golgi apparatus

Storing, packaging, and shipping of proteins - looks like stacks of hollow pancakes and is constructed of folded membranes. Within these membranes, cellular products are stored or packaged by closing off a bubble of membrane with the proteins or lipids inside. These are shipped (via ER) to the part of the cell where they will be used, or to the cell membrane for secretion from the cell

Types of genes encoded

Structural & Regulatory

Centrioles

Structural components of may cells and are common in animal cells - tubes costructed of microtubules a pinwheel shape; responsible for generation of new microtubules; primarily the formation of a structural skeleton around which cells divide during mitosis

Substrate

Substance in enzyme that fits within active site

Passive Transport

Substances freely pass through membrane without expending any energy

Genomes

Sum total of genetic information

Nucleus parts

Surrounded by 2 lipid bilayer membranes; contains chromosomes, nuclear pores, nucleoplasm, and a nucleolus

Cellular Respiration

Takes place in mitochondria - Breakdown of covalent bonds within sugar molecules with the intake of oxygen and release ATP; reactions occur along the folds of the internal membrane called Cristae

Steps of Protein synthesis

Transcription & Translation

Genetic makeup of bacteria can be changed through what 2 processes

Transduction & Transformation

Transduction

Transfer of genetic material from one bacterial cell to another (mediated by bacteriophage - virus that targets bacteria)

Active Transport

Transport requiring energy output from cell to move molecule against a concentration gradient (which is the opposite direction they would go through in diffusion under normal circumstances) - with the addition of ATP, a protein molecule embedded in the membrane changes shape and moves a molecule across the membrane

Active site

Uniquely shaped area of enzyme.

Codon

Unit of 3 nucleotides that encodes a particular amino acid

Phospholipid Bylayer

What cell membrane is made out of (plus carbs & proteins); allows for selective permeability which manages concentration of substances within cell

Transformation

When bacteria absorbs and incorporates pieces of DNA from environment

Enzyme-substrate complex

When substrate is seated in active site.

Isomotic/Isotonic

When water concentration is equal on both sides of membrane

Centromere

Where chromatids remain attached

Schleiden & Schwann

developed cell theory

Gamete

egg & sperm - 4 haploid cells produces in meiosis

Glycolysis reaction equation

glucose (6C) + 2ADP + 2P + 2NAD => 2 puruvic acid (3 C each) + 2ATP + 2 NADH + 2H-

Electron Microscope

must use to see all types of cells

Translation

tRNA is required for protein synthesis; Translation occurs at ribosomes; Ribosome attaches to mRNA at the start codon (which is only recognized by certain initiator tRNA). Ribosome adds tRNA whose anticodons make complementary bonds with next codon on mRNA string, forming peptide bond between amino acids as each amino acid is held in place by a tRNA. At end of translation, terminating codon stops synthesis process and protein released.