t3

Question 1

robert hooke and cells
what year?
what did he do?

Answer 1

year : 1665
he built microscopes to examine thin sections of dried cork samples from plants - names cavities cells

Question 2

cell theory

Answer 2

• all organisms are made up of cells
• the cell is the fundamental unit of life
• cells come from pre-existing cells

Question 3

prokaryotic cells

Answer 3

prokaryotic cells lack a nucleus and have no internal compartmentalization

Question 4

eukaryotes cells

Answer 4

eukaryotic cells have a nucleus and internal membrane-bound organelles

Question 5

hopaniods

Answer 5

-located in membranes of bacteria
- modulate the fluidity of the membrane bilayer
-increase rigidity of the membrane

Question 6

cholesterol

Answer 6

• found in animal cell membranes
• both polar and non polar regions
• impact membrane fluidity

Question 7

all cells are defined by a cell man brand (lipids)

Answer 7

• lipids found in the cell membrane are phospholipids
• phospholipids have a hydrophobic tail (non polar region) and hydrophilic head (polar region)

Question 8

lipid structures micelle

Answer 8

formed by phospholipids with large bulky heads and a single hydrophobic tail

Question 9

lipid structure bilayer

Answer 9

bilayers and liposomes are formed by phospholipids with small heads and 2 hydrophobic tails

Question 10

lipid structure phospholipid

Answer 10

when in water phospholipid spontaneously form a liposome, wherein polar heads and non polar tails associate with one another in a bilayer

Question 11

membranes

Answer 11

membranes are self-healing because they will spontaneously reform

Question 12

membranes are a fluid mosaic

Answer 12

• lipids and proteins are found in the membrane, forming a mosaic
• pupils are able to move laterally within the membrane
• lipid movement is affected by the nature of the phospholipid tails

Question 13

saturated vs unsaturated

Answer 13

• van der waals interactions between the fatty acid tails help stabilize the membrane
• bc these interactions are weak, membrane lipids are able to move in the plane of the membrane, thus membrane is fluid

Question 14

cholesterol

Answer 14

• found in many animal cell membranes
• both polar and non polar regions
• impact membrane fluidity

Question 15

cholesterol and fluidity

Answer 15

cholesterol acts like a “buffer” for membrane fluidity

Question 16

proteins in the membranes: transporters and receptors

Answer 16

• transporters that move ions and molecules
• receptors that allow the cell to receive signals from the environment

Question 17

proteins in the membrane: enzyme and anchors

Answer 17

• enzyme that catalyze chemical reactions in a cell
• anchors that attach to other proteins such as actins or cytoskeleton that help to maintain cell structure and shape

Question 18

integral proteins

Answer 18

• integral membrane proteins are permanently associated with the membrane and can cross the entire membrane

Question 19

peripheral proteins

Answer 19

• peripheral membrane proteins are temporarily associated with either side of the membrane

Question 20

examples of integral membrane proteins

Answer 20

• sodium-potassium pump
• aquaporins
• ATP synthase

Question 21

examples of peripheral membrane proteins

Answer 21

• cytochrome c
• phospholipase
  glycolipid transfer proteins

Question 22

evidence for the fluid mosaic model: is there movement in the membrane?

Answer 22

• proteins are fluorescently labeled
• one specific region of the membrane is targeted by a laser and photo bleached
• researchers than observe the membrane to see if the bleached area remains, or if fluorescent proteins return to the bleached area

Question 23

protein ls do move in the membrane

Answer 23

• fluorescence returns to the bleached area, showing that proteins are mobile throughout the membrane

Question 24

cell membranes

Answer 24

• the cell to the right is a pancreatic cell. the cell is surrounded by a cell membrane which defines the shape and size of the cell

Question 25

is the cell membrane impermeable?

Answer 25

• all cells are enclosed by a plasma membrane that serves as a boundary defining the space of the cell
• the cell membrane is selectively permeable

Question 26

selective permeability of cell membranes

Answer 26

• freely permeable: small gas molecules such as oxygen, nitrogen, and co2
• somewhat permeable: small, uncharged polar molecules such as water, ethanol, and glycerol
• impermeable: large, uncharged polar molecules such as glucose and sucrose
• ions such as h+, na, k, cl, etc

Question 27

simple diffusion: passive transport across the permeable membrane

Answer 27

• movement of molecules from an area of high conc to an area of low conc
• passive transport does not require expenditure of energy from the system

Question 28

osmosis

Answer 28

-water movement across a permeable membrane (ie. diffusion specific to water)
- movement of water from an area of low solute to high solute

Question 29

facilitated diffusion (energy not required) ; movement down a concentration gradient through a channel or carrier

Answer 29

• during facilitated diffusion in cells, molecules and substances move from high conc to low conc throughout transporters embedded in the membrane

Question 30

active transport

Answer 30

• when cells need to move substances against their conc gradient, energy must be expanded

Question 31

primary active transport

Answer 31

• in primary active transport, the na/k pump uses energy released from hydrolysis of atp to move 3 na ions and 2k ions against the conc gradient
• energy stored in the conc gradient can produce an electrochemical gradient to drive the movement of other molecules through secondary active transport

Question 32

secondary active transport

Answer 32

• antiporter: h ions return into the cell to exchange for the export other positive ions or molecules such as na
• because the movement of the coupled ions or molecules is driven by the movement of protons and not atp, the transports is called secondary active transports

Question 33

maintaining cell shape

Answer 33

• cell shape and size in red blood cells change based on the solute conc surrounding the cells
• red blood cells use active transports of ions to keep the internal environment of the cell isotonic to the external environment

Question 34

maintaining cell shape part 2

Answer 34

• in some single-called organisms, cells contain a contractile vacuole, an organelle
• the contractile vacuole absorbs excess water in the cell and expels it to prevent cell lysis

Question 35

maintaining cell shape: cell walls

Answer 35

• the cells of many different organisms contain a cell wall, a structure that helps to maintain the cell shape
• the cell wall can be made up of many different compounds but the function of the cell wall is similar in each organism with the structure

Question 36

cell walls and turgor pressure

Answer 36

• the cell wall provides structural support and protection
• turgor pressure within the cell occurs when water moves into the cell through osmosis

Question 37

plant cell that animal cell doesn’t have

Answer 37

• cell wall: provides additional support to the cell
• vacuoles: contribute to the structure of the cell by maintaining turgor pressure
• chloroplasts: convert the energy from sunlight into chemical energy that the cell can use

Question 38

cell organelles: the nuclear envelope

Answer 38

• the nuclear envelope is a double membrane that surrounds the nucleus
• the membrane is perforated by protein openings called nuclear pores, which allow molecules to move into and out of the nucleus
• these pores are essential for the nucleus to communicate with the rest of the cell