AS Booklet 3- Viruses, Cell Structure, Cell Transport and Mitosis Flashcards

Question

How do you calculate the size of cellular structures (microscope formula)?

Answer 1

IMA Image = magnification x actual. Actual size = real life size. Image size = magnified size.

Answer 2

mm-µm-nm | x 1000 each time or divide 1000.

Answer 3

Phospholipid bilayer: • Phospholipids in two layers, hydrophobic fatty acid tails facing outwards and hydrophilic phosphate heads facing onwards towards each other. • Cholesterol embedded in membrane. • Proteins embedded in membrane. • Carbohydrate chains, often forming glycolipids and glycoproteins due to being attached to lipids or proteins, respectively. • Unsaturated and saturated fatty acids.

Answer 4

Small, large, charged. • Small molecules such as CO2 and O2 can diffuse between the gaps between molecules of the phospholipid bilayers. H2O can pass through aquaporins by osmosis. • Carrier Proteins allow specific/certain molecules through by facilitated diffusion and active transport. • Channel Proteins allow specific/certain molecules through by facilitated diffusion. • Water soluble ions and polar ions cannot pass through cell membrane. • Lipid soluble molecules can pass through the cell surface membrane, bad because harmful molecules such as benzene can get into cell.

Answer 5

Diffusion, active transport and facilitated diffusion. • Diffusion is passive (does not require energy from respiration). • Facilitated diffusion is passive. • Active transport is active, so requires energy from the hydrolysis of ATP.

Answer 6

The net movement of molecules from a high concentration to a low concentration. Doesn’t use energy.

Answer 7

Allows the transport of polar molecules such as glucose and amino acids across membranes down a concentration gradient. In Carrier Proteins, molecule fuses with protein to cause a change in the tertiary structure which allows the protein to pass through. In Channel Proteins, there is no shape change.

Answer 8

Movement of molecules or ions through partially permeable membranes. Phosphate group from energy in ATP attaches to carrier protein and activates protein to accept the particle to be transported. Energy of the phosphate group attaching to the protein is used to change the shape, transporting the molecule.

Answer 9

The net movement of water molecules from a high concentration to a low concentration.

Answer 10

The potential of water molecules to leave a solution by osmosis. Higher water potential —> lower water potential. Pure water = 0 Less negative = more water. More negative = less water. If a cell is in a solution with a higher water potential, the cell will lose water via osmosis and plant cells become plasmolysed (cell membrane comes away from cell wall). If a cell is in a solution with a lower water potential, the cell will gain water via osmosis and this can result in the cell bursting (osmolysis).

Answer 11

Deoxyribose nucleic acid is genetic material wrapped around histones (protein). Chromosomes are thread-like structures that DNA is organised into during cell division (in eukaryotes).

Answer 12

Mitosis is the process by which two new (daughter) cells are created from a single (parent) cell. The stages of mitosis are interphase, prophase, anaphase, metaphase, telophase followed by cytokinesis.

Answer 13

Interphase: - DNA content is doubled, as are organelles. - Increase in protein synthesis. Prophase: - Chromosomes joined by centromeres. They shorten and thicken. - Centrioles move to opposite poles (not present in plant cells). - Nuclear membrane breaks down. Metaphase: - Centrioles form spindles (consists of protein microtubules). - Chromosomes move to equator of spindle and attaches via centriole. - Sister chromatid orientated towards opposite poles of the cell, horizontal. Anaphase: - Centromere splits, sister chromatids separated and pulled to opposite poles of the cell by the spindles. Telophase: - Chromatids at opposite ends of cell begin to uncoil. - Nuclear membrane reforms. Cytokenesis: - The splitting of the cytoplasm into two, with the cell membrane

Answer 14

Uncontrolled growth can lead to cancer. Uncontrolled growth occurs when the cell cycle is not regulated due to mutations in the genes (proto-oncogenes and tumour-suppressor genes). This could result in a cell being in the interphase section of the cycle much, much shorter than usual so that they can rapidly divide, forming a tumour.

Answer 15

Binary Fission. The circular DNA and plasmid DNA is replicated. The cell elongates as this happens. The cell wall and plasma membrane divide and the cells separate. Identical daughter cells.

Answer 16

Population in the nth generation = 2 to the power of n (2^n). n = number of generations so after 4 generations the population would be: 2^4 = 2 x 2 x 2 x 2 = 16 cells.

Answer 17

Nuclei. Mitochondria and chloroplasts. ER, ribosomes.

Answer 18

Resolution: ability to distinguish between two close objects. Artefacts: False images arising from poor technique.

Answer 19

* Molecules of phospholipid move creating fluid structure. * Proteins in membrane are unevenly distributed, creating mosaic. * Partial permeability due to proteins and phospholipids in membranes. * Proteins act as carrier or channel proteins. * Some proteins act as specific receptors to hormones. * Glycolipids and glycoproteins act as both receptors and also as antigens in cell-cell recognition. * Cholesterol restricts movement of phospholipids so membrane is less fluid and less ions are lost.

Answer 20

Rate of diffusion is PROPORTIONAL TO surface x concentration difference ———————————————— Thickness of exchange surface Concentration difference = gradient.