Bio Exam 3-1 Review Flashcards
(40 cards)
Oxidation
–An electron is lost –Cells oxidize organic compounds to drive metabolism –During Respiration, glucose is oxidized to CO2 –In metabolism, oxidation is often associated with a gain of oxygen or a loss of hydrogen
Reduction
–Accepting electrons –Oxygen is removed –Hydrogen is added –Always occurs accompanied by oxidation of the reducing agent
Cell Respiration
–During cell respiration, glucose is oxidized to CO2 –The oxidation of organic compounds to extract energy from chemical bonds (put more simply, cellular respiration is the process by which energy is harvested)
Glycolysis
–Occurs in the cytoplasm –Converts glucose into two 3-carbon molecules of pyruvate Step A: Glucose priming: Requires the cell to use two ATP molecules Step B: Cleavage and rearrangement Step C: Oxidation: NADH is formed from G3P and NAD+ Step D: ATP generation –The control point for glycolysis is the enzyme phosphofructokinase
Aerobic Respiration
–Cell gains energy –Oxygen is present –Oxygen is an excellent electron acceptor –Occurs in the mitochondria –Also known as aerobic metabolism –ATP is produced –Uses oxygen as the **final electron acceptor
Fermentation
–When oxygen is unavailable, an organic molecule can accept electrons instead –Does not have to occur in an anaerobic environment –The process of deriving energy from the oxidation of organic compounds
The Krebs Cycle
–AKA the Citric Acid Cycle –The two-carbon acetyl group of acetyl-CoA combines with a four-carbon molecule called oxaloacetate. Segment A: Acetyl-CoA plus oxaloacetate; produces the six-carbon citrate molecule Segment B: Citrate rearrangement and decarboxylation; two NADH and one ATP are produced Segment C: Regeneration of oxaloacetate; NADH and FADH2 produced
The Electron Transport Chain
–The NADH and FADH2 molecules formed during aerobic respiration each contain a pair of electrons that were gained when NAD+ and FAD were reduced. The NADH molecules carry their electrons to the inner mitochondrial membrane, where they transfer the electrons to a series of *membrane-associated proteins, collectively called the electron transport chain, or ETC. –ATP synthase catalyzes a reaction to generate ATP –Located in the inner mitochondrial membrane
Chemiosmosis
–The diffusion of ions across a selectively-permeable membrane –The newly formed ATP is transported by facilitated diffusion to the many places in the cell where enzymes require energy –The energy released by the reactions of cellular respiration drives the proton pumps that produce the proton gradient –The proton gradient provides the energy required for the synthesis of ATP
Autotrophs & Heterotrophs
Autotrophs: convert energy from sunlight to organic molecules Heterotrophs: Use organic compounds made by autotrophs
Metabolism
–The set of chemical reactions that occur in living organisms to maintain life –These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments Category 1:Catabolism: breaks down organic matter, for example to harvest energy in cellular respiration Category 2: Anabolism: uses energy to construct components of cells such as proteins and nucleic acids
Binary Fission
–AKA prokaryotic fission, is the form of asexual reproduction and cell division used by all prokaryotic and some single-celled eukaryotic organisms. – Simple form of cell division –Occurs in bacteria –Chromosome must be replicated, and then the products partitioned to each end of the cell prior to the actual division of the cell into daughter cells
Eukaryotic Chromosomes
–40% DNA –60% protein –A typical human chromosome contains about 140 million nucleotides in its DNA –Human cells have 46 chromosomes (23 pairs)
Eukaryotic Cell Cycle
–The process involves the duplication of the genome, its accurate segregation, and the division of cellular contents –Divided into five main phases 1: G1 (Gap phase 1): primary growth phase 2: S (Synthesis): cell synthesizes a replica of the genome 3; G2 (Gap phase 2): second growth phase **G1, S, and G2 are INTERPHASE, the portion of the cell cycle between cell divisions 4: M (Mitosis): Separation of the 2 daughter genomes 5: C (Cytokinesis): Cytoplasm divides, creating 2 daughter cells
Mitosis
–The process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei. –Five stages: 1: Prophase 2: Prometaphase 3: Metaphase 4: Anaphase 5: Telophase
Cancer & the p53 Gene
–Cancer is a failure of cell cycle control –The unrestrained, uncontrolled growth of cells in humans. –A disease of cell-division –p53 is a culprit of cancer, this gene plays a key role in the G1 checkpoint of cell division –If p53 detects DNA damage, it halts cell division and stimulates the activity of special enzymes to repair the damage. –Scientists have found that p53 is entirely absent in the majority of cancerous cells they have examined, so cancer cells are able to repeatedly undergo cell divi
Meiosis
–A process of reductional division in which the number of chromosomes per cell is cut in half –During meiosis, the genome of a diploid germ cell, which is composed of long segments of DNA packaged into chromosomes, undergoes DNA replication followed by two rounds of division, resulting in **four haploid cells.
Bacteriophages
–AKA phages –Viruses that infect bacteria
Chargaff’s Rule
1) The proportion of A always equals that of T, and the proportion of G always equals that of C, or A=T, G=C 2) It follows that there is always an equal proportion of purines (A and G) and pyrimidines (C and T)
Watson & Crick
–They did not perform a single experiment themselves related to DNA structure; rather, they built detailed molecular models based on the information available –The key to their model was Watson & Crick’s understanding that each DNA molecule is actually made up of TWO chains of nucleotides that are intertwined- the double helix
DNA Structure
Three main components 1) A five-carbon sugar 2) A phosphate group 3) A nitrogen-containing (nitrogenous) base (may be a purine [adenine, A, or guanine, G], a two-ringed structure, or a pyrimidine [thymine, T, or cytosine, C], a single-ringed structure).
Helicase
–Unwinds the double helix
Primase
–Synthesizes RNA primers
Single-strand binding proteins
–Stabilizes single-stranded regions
