Why did the cytoplasm fraction produce lactic acid in the presence of both glucose and pyruvate? Why did the mitochondria produce carbon dioxide in the presence of pyruvate but not in the presence of glucose? The figures to the right display the absorption range for several different pigments found in plants (top) and the rate of photosynthesis at varying conditions of wavelength in one plant species (bottom): What color and wavelength of light is reflected by the plant species tested? How do you know? What wavelength(s) increase the rate of photosynthesis in the plant species tested? What pigment does this correspond to? How do you know? CONCEPT 4 – THE CELL CYCLE AND HEREDITY Cell cycle Reason for division- as cells increase in volume, the surface area decreases and demand for material resources increases which limits cell size Smaller cells have a more favorable surface area-to-volume ratio for exchange of materials with the environment (diffusion, etc.). High SA:V ratio is favorable. Ex. 6:1 is better than 6:5 Cell cycle switches between interphase and cell division. Interphase has three phases: growth (G1), synthesis of DNA (S) and preparation for mitosis (G2). During mitosis duplicated chromosomes line up in center with spindle fibers attached to help pull them apart. Duplicated chromosomes are pulled apart by spindle fibers. Cytokinesis-division of cytoplasm and reformation of cell membrane. Animal cell- pinches in (cleavage) using microfilaments; plant cell- form cell plate reforms cell wall. The cell cycle is directed by internal controls or checkpoints. Internal (enzymes and promoting factors) and external signals (growth factors) provide stop and- go signs at the checkpoints. Ex. Mitosis-promoting factor (MPF) Cancer results from disruptions in cell cycle control (too much division, defective tumor suppressor genes, overactive genes) which are a result of DNA damage to proto-oncogenes (regulatory genes) which make products like cyclins and cyclin-dependent kinases. Cells spend different amounts of time in interphase or division. Nondividing cells may exit the cell cycle; or hold at a particular stage in the cell cycle. Mitosis is used for growth and repair in animals; plants use mitosis to make gametes and for growth or repair.
DNA DNA ligase DNA polymerase DNA replication exons genetic code helicase hydrogen bonding inducible introns lagging strand leading strand RNA (miRNA) mutation nucleic nucleotides Okazaki fragments protein replication fork repressor RNA (mRNA, rRNA, tRNA) start codon/stop codon template strand transcription transcription factors translation Thinking Questions Compare the two DNA sequences shown below. Transcribe them into mRNA and translate them into an amino acid sequence. mRNA GTG CAC CTC ACT CCA GAG GAG (Normal Hemoglobin) amino acids GTG CAC CTC ACT CCA GTG GAG (Sickle Cell Hemoglobin) mRNA amino acids Circle any differences there are in the DNA, RNA and amino acid sequences that might exist between these two sequences. Identify the type of mutation that is represented AND EXPLAIN, IN DETAIL, what effect this would have on the protein/pigment (be sure to mention the types of functional groups on the amino acids and how this would affect shape of the molecule). In prokaryotic cells, translation begins before transcription is finished. Give two reasons why this would not be possible in eukaryotic cells. The restriction enzyme cleaves double-stranded DNA at the sequence 5'-GAATTC-3' and the restriction enzyme HindIII cleaves at 5'-AAGCTT-3'. A 20 kb circular plasmid is digested with each enzyme individually and then in combination, and the resulting fragment sizes are determined by means of electrophoresis. The results are as follows: