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BIOLOGY 1110
BIOLOGY
FUNDAMENTAL
S
MIDTERM 1
REVIEW
Q & A
Describe the types of bonds within a water molecule and between different water molecules. How/why are these bonds important?
- Polar covalent bonds: O is more electronegative than H, O is on the top with 2 hydrogens coming out on the bottom
- Hydrogen bonds: the slight positive charge on the H atom of one water molecule attracts the slight negative charge on the O of a neighboring water molecule—based on polar covalent bonds Class of Molec ule Building Blocks (Monomers) Bonds formed Functions and examples
Lipids (fats) glycerol long strand of H-C bonds saturated is all single bonds unsaturated is bent with at least 1 double bond Storage for energy, components of cell membranes, fat soluble vitamins Nucleic Acids nucleotide phosphate group, sugar (pentagon), and nitrogenous base- A,C,G,T (in DNA) or U (in RNA) Store and transfer genetic information Carbohydrat es Simple sugar (monosacchar ide) Monosaccharide: one hexagon, disaccharide: 2 hexagons, polysaccharides: multiple hexagons Provide the body with energy Proteins Amino acid Amino group on the left (NH2 or NH3), carboxyl on the right (COO or COOH), R group in the middle Do most of the work within the cell
Why is protein structure important for protein function?
- The function of a protein is determined by its shape. The shape of a protein is determined by its primary structure (sequence of amino acids). The sequence of amino acids in a protein is determined by the sequence of nucleotides in the gene (DNA) encoding it
What type of bond holds the nucleotides together? What bonds hold two strands of DNA together?
- Two strands are held together by hydrogen bonds between bases
- Complimentary base pairing occurs between A & T, G & C Compare and contrast prokaryotes and eukaryotes.
- All cells have: genetic material, ribosomes, cytoplasm, cell membrane
- Prokaryotes: most ancient forms of life, small, lack a nucleus
- Eukaryotes: much larger, genetic material is in the nucleus, cytoplasm with other organelles, can be multicellular or unicellular Compare and contrast animal and plant cell.
- Both: nucleus, membrane, ribosomes, golgi apparatus, ER (rough is studded with ribosomes), cytosol
- Animal cell: lysosomes
- Plant cell: chloroplasts, vacuoles, cell wall Describe the main function(s) of each organelle.
- Membrane: encloses the cell, forms barrier, regulates passage of substances in and out of cell, maintains homeostasis
- Nucleus: houses genetic material and DNA, nuclear envelope separates nucleus from cytoplasm, nucleolus (center of nucleus) synthesizes rRNA, mRNA is duplicated DNA to travel through the cell
- Ribosomes: manufactures proteins, some float in cytosol (free), others attach to rough ER membrane (bound)
- ER: extension of nuclear envelope, rough (synthesizes proteins, has bound ribosomes, folding of phospholipid bilayer), smooth (lacks ribosomes, synthesizes lipids and stores calcium ions)
- golgi apparatus: sacs called cisternae, modifies products of ER, sorts and packages materials in transport vesicles
- lysosomes: main source of digestion for macromolecules, only in animal cells, digestive enzymes, separates organelles in an acidic
Explain what is hyper/hypo/isotonic and what you predict would happen to a cell placed in each condition.
- Isotonic: solute and solvent concentration are the same, no net water movement
- Hypertonic: solvent > solute concentration, water wants to rush out of cell (less concentrated)
- Hypotonic: solute > solvent concentration, water wants to go into the cell (more concentrated) What substances can pass the membrane without the aid?
- Small and nonpolar (hydrophobic) molecules can freely pass through the membrane, but charged ions and large molecules such as proteins and sugars are barred passage What is active transport? Why do we need to consider concentration gradient?
- A concentration gradient is created by a difference in solute concentration—there is a net movement from high concentration regions to low concentration region regions
- Active transport: moves from low to high concentration, requires energy and moves against the concentration gradient What is ATP?
- Nucleotide that temporarily carries energy, formed during cellular respiration through exergonic reactions
- Cells use potential energy stored in food to make ATP, which is the immediate source of energy in your body and powers work What is the difference between kinetic and potential energy?
- Kinetic: energy of motion/movement
- Potential: stored energy (available to do work, waiting to be used later) How do enzymes work? What type of macromolecule are they (usually)?
- Enzyme: a protein that acts as a catalyst, speeding up a reaction
- Each enzyme fits the shape of a substrate—helps the bonds break and speeds up reaction
- Enzymes lower the activation energy barrier—does not change the amount of energy How can enzyme activity be affected?
- Most enzymes are active within a range of temperatures, with an optimal temperature at which their activity is the greatest
- Enzymes also have optimal salt concentrations and pH, at which they function most quickly
- Inhibitors lower enzyme activity, preventing unneeded reactions from taking place— competitive inhibitors block access to the access site, noncompetitive inhibitors change the shape of the active site, metabolic pathways are regulated by feedback inhibition How is cellular respiration and photosynthesis related? Draw concept map-see big picture!
- We breathe to get oxygen to our cells so that they can use oxygen to make cellular energy (ATP). Cells do this by completely breaking down glucose (sugar) into carbon dioxide (which you breathe out) and water. What is electron transport chain?
- Where energy from the electrons is used to produce many ATP
- As electrons travel through the ETC, carrier molecules use the potential energy of the electrons to transport hydrogen ions into the intermembrane compartment
Where does the energy for ATP synthesis come from (most directly)?
- The hydrogen (proton) gradient is used to synthesize ATP What is fermentation?
- In the absence of oxygen, cells can use anaerobic respiration or fermentation
- Alcoholic fermentation (microbes): NADH reduces pyruvate to ethanol, NAD+ is recreated
- Lactic acid fermentation (bacteria and muscle cells): NADH reduces pyruvate to lactic acid, NAD+ is recreated Photosynthesis IN OUT Overall Reaction light energy, CO2, chlorophyll Oxygen, glucose Light Reactions Light, H2O, NADP+, ADP
O2, NADPH, ATP
Carbon Cycle ATP, CO2, NADPH ADP, NADP+, glucose Why do most plants appear green?
- Certain colors are reflected by light, all other colors are absorbed (people see the color that is reflected)
- Most common pigment is chlorophyll, which reflects green light Why do we need electron carriers in both cellular respiration and photosynthesis?
- As electrons travel through the transport chain (both cellular respiration and photosynthesis), carrier molecules use the potential energy of the electrons to transport hydrogen ions into the intermembrane component What does it mean semiconservative DNA replication model?
- When DNA unwinds, each strand is a template to “attract” complimentary
- A primer is a short single strand of RNA or DNA that serves as a starting point for DNA synthesis. It is required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA.
- DNA replication always goes from 5’ to 3’ What are the stages of the cell cycle?
- G1: normal cell function and cell growth
- S: DNA replication
- G2: additional growth and preparation for division
- Prophase: chromosomes condense and become visible, spindle forms as centrosomes move to opposite poles (no crossing over)
- Prometaphase: nuclear envelope breaks up, spindle fibers attach to kinetochores on chromosomes
- Metaphase: chromosomes line up along equator of the cell
- Anaphase: two sister chromatids part suddenly, two daughter chromatids move towards opposite ends and the cell elongates
- Telophase: two daughter nuclei reform with new nuclear envelopes, chromosomes become less condensed, nuclear envelope and nucleolus form at each pole and spindle disappears
- Cytokinesis: cytoplasm splits What is the product of mitosis? Why we need mitosis?
- Product: two daughter cells that are exact copies of the parent cell
- Mitosis produces new cells and replaces cells that are old, lost, or damaged What is cancer? (Characteristics of cancer cells)
- Cancer cells continue to divide when they don’t need to, and override the checkpoints
- Compared to regular body cells, cancer cells have distinct features:
- They lose specialization
- They are “immortal” in that they can continue to divide endlessly
- They can regenerate the ends of their chromosomes
- They lost their contact inhibition features
- They can develop new blood vessels which “feed” tumors What is the difference between sexual and asexual reproduction?
- Asexual reproduction: cell division which results in genetically identical cells—binary fission and mitosis
- Sexual reproduction: cell division which yields non-identical daughter cells—gametes are produced by meiosis
What is chromosome? How many chromosomes can be found in human skin cell? What about human egg?
- Chromosome: thread-like structures located inside the nucleus of animal and plant cells, made up of protein and DNA
- Human skin cell: 23 pairs of chromosomes, 46 total
- Human egg cell: 23 total chromosomes Recall
replication while RNA Polymerase is used during transcription to synthesize the mRNA strand and joins together the RNA nucleotides (5’ to 3’) Why do we need t-RNA?
- The purpose of tRNA is to bring amino acids to the ribosome for protein production. To make sure that the amino acids are added to the protein in a specific order, the tRNA reads the codons from mRNA. What is the function of the ribosome?
- The ribosome is where translation takes place and where the genetic code is read What is mutation?
- A change in a cell’s DNA sequence—may occur in coding region or regulatory region, can increase or decrease fitness
- Most popular kinds of mutation: point (change one or a few base pairs), frameshift (insertion or deletion of one nucleotide) What is an operon? Do operons exist in eukaryotes?
- Groups of genes that are always transcribed together that can be coordinately controlled by a single “on-off” switch
- They exist in prokaryotes but not eukaryotes What stages in gene expression can be regulated in Eukaryotic cell?
- DNA availability
- Transcription factors
- Intron removal and other mRNA processing Do you have the same DNA in all of your cells? Why do they look differently?
- All the cells in a person's body have the same DNA and the same genes. However, the difference between cells in different tissues and organs is that the "expression" of the genes differs between cells. Expression means that the message from the DNA is being copied and made into protein. Explain Mendel law of segregation and law of independent assortment.
- Law of segregation: the alleles of the gene separate during gamete formation. Each gamete contains only one allele from each gene pair. The two members of each gene pair must separate during meiosis in the parents into different gamete cells
- Law of independent assortment: the segregation of alleles for one gene does not influence the segregation of alleles for another gene How are Punnett squares helpful in following inheritance of single genes?
- Helps reveal which alleles the offspring may inherit—summarizes meiosis and fertilization
- Inheritance of characters by a single gene may deviate from Mendel in case of incomplete dominance (intermediate phenotype, blending), codominance (heterozygous, no blending), pleitropy (one gene has multiple effects on the phenotype) Explain the relationship between dominant and recessive alleles of a gene.
- Dominant: exert their effects whenever they are present (capital letter)
- Recessive: effect is masked if a dominant is also present (lowercase letter) How can we use the multiplication rule to predict inheritance patterns for two or more genes?
- Example: Rr Yy Tt x Rr Yy Tt what are the chances of being Rr Yy Tt
- Split up into 3 punnett squares and get the chances for each
- One type of organism can express a gene from another species
- Transgenic organisms receive recombinant—a molecule with DNA from two different sources
- Transgenic organisms have many useful application, such as manufacturing pharmaceuticals, engineering hardy crops, and testing human genetic diseases How do researchers determine a sequence of DNA?
- DNA sequencing reveals a complete nucleotide sequence of a DNA molecule
- Researchers put the unknown DNA sequence, primers, nucleotides, and replication enzymes together How does PCR work, why it is useful tool?
- Polymerase chain reaction: can produce many copies of a specific target segment of DNA
- The key to PCR is an unusual, heat-stable DNA polymerase called Taq polymerase
- A 3 step cycle (heating, cooling, and replication) brings about a chain reaction that produces an exponentially growing population of identical DNA molecules What is gel electrophoresis?
- Gel electrophoresis is a laboratory method used to separate mixtures of DNA, RNA, or proteins according to molecular size. In gel electrophoresis, the molecules to be separated are pushed by an electrical field through a gel that contains small pores. The molecules travel through the pores in the gel at a speed that is inversely related to their lengths. This means that a small DNA molecule will travel a greater distance through the gel than will a larger DNA molecule.
