1 Flashcards
DNA Replication
Helicase unwinds DNA into single strands allowing each strand to be copied. Gyrase unwinds the supercoil to prevent DNA from breaking. Single stranded binding proteins keep the DNA strands separated and stabilized. Primase adds RNA nucleotides/primers to the complementary base pairs. DNA Polymerase III synthesizes the leading strand of DNA and the okazaki fragments. DNA Polymerase I digests RNA nucleotides and replaces them with DNA nucleotides. Ligase joins the okazaki fragments on the lagging strand to form a single strand of DNA.
Prokaryotic cells versus eukaryotic cells
Prokaryotic cells are smaller, whereas eukaryotic cells are larger. Prokaryotic cells have no membrane bound organelles, whereas eukaryotic cells do have membrane bound organelles. Prokaryotic cells have DNA in their nucleoid, whereas eukaryotic cells have DNA in their nucleus. Prokaryotic cells have 70S ribosomes, whereas eukaryotic cells have 80S ribosomes. Prokaryotic cells divide by binary fission, whereas eukaryotic cells divide by binary fission, mitosis, or meiosis.
Endocytosis versus exocytosis
Endocytosis is the process of a cell’s membrane engulfing a substance. Exocytosis is the process of the cell’s membrane fusing with vesicles to remove substances out of the cell.
Pinocytosis vs phagocytosis
Pinocytosis or “cell drinking” allows the cell to take in liquid substances through small vesicles. Phagocytosis or “cell eating” allows the cell to take in solid substances through large vesicles.
Louis Pasteur experiment
Louis Pasteur tested for spontaneous generation. He found that after applying heat to a broth filled flask with a long neck curved downward, bacteria would not grow. His experiment showed that microbes cannot arise from nonliving materials.
Passive transport versus active transport
Passive transport requires energy to move molecules along the concentration gradient. Active transport requires energy to move molecules against the concentration gradient.
Simple diffusion versus facilitated diffusion
Simple diffusion is the transport of molecules across the cell membrane without the use of membrane proteins. Facilitated diffusion is the transport of molecules across the cell membrane that requires the use of membrane proteins.
Davson-Danielli model
The Davson-Danielli model proposed that the cell membrane was composed of a phospholipid bilayer between of 2 layers of globular proteins.
Singer-Nicolson model
The Singer-Nicolson model suggested that membrane proteins are individually embedded in the phospholipid bilayer instead of laying on both sides.
Cholesterol
Cholesterol is a steroid that controls membrane fluidity by restricting movement of phospholipids to other molecules to prevent solidification.
Surface area to volume ratio in cells
When the surface area of a cell is greater than its volume, it allows for materials to be more efficiently transported.
Endosymbiotic theory
The endosymbiotic theory explains the origin of eukaryotic cells. It states that eukaryotic cells came from prokaryotes that were originally taken in by larger prokaryotic cells and remained inside host cells instead of being digested/broken down. Evidence of the endosymbiotic theory are chloroplasts and mitochondria.
Cell theory
Cell theory includes the ideas that the cell is the basic unit of life, all living things are composed of cells, cells come from preexisting cells.
DNA vs RNA
DNA is double-stranded, whereas RNA is single-stranded. DNA contains deoxyribose, whereas RNA contains ribose. DNA uses the base thymine, whereas RNA uses the base uracil.
Cohesion versus adhesion
Cohesion is the attraction of molecules of the same substance. Adhesion is the attraction of molecules of two different substances.
