Module 1: Cells as the basis of life Flashcards

Question

flagellum | plant and animal ?

Answer 1

plant and animal | Helps with movement of substances across cell surfaces

Answer 2

A beam of light passes through the thin specimen on a slide. Produces images up to 1500X magnification (size) Maximum resolution of 200 nm (clarity)

Answer 3

Light microscopes are used to study living cells and for regular use when relatively low magnification and resolution is enough.

Answer 4

Structures beyond the limit of resolution of the light microscope can be viewed. Sample to be viewed is labeled with fluorescent substances that will attach to the structures that the scientist wants to observe. The sample is illuminated with high-intensity light that causes the fluorescent substance to emit light.

Answer 5

It provides detailed images of the surfaces of cells (3D) and whole organisms that are not possible by TEM. It can also be used for particle counting and size determination, and for process control.

Answer 6

Uses an electron beam instead of light (photons) and gives a much greater magnification and resolution than light microscopes.

Answer 7

The transmission electron microscope is used to view thin specimens (tissue sections, molecules, etc) through which electrons can pass generating a projection image. (2d)

Answer 8

digital image manipulation tagging structures with fluorescent dyes enhancing contrast using phase-contrast

Answer 9

(a measure of the ability of a substance to pass through the membrane)

Answer 10

a) Size b) electrical charge c) lipid solubility

Answer 11

Small molecules move across membranes fast.

Answer 12

Water-soluble (hydrophilic) molecules have difficulty penetrating a membrane.

Answer 13

Lipid-soluble molecules do not have trouble penetrating the membrane ; for example, urea and ethanol have high permeability.

Answer 14

Electrically-charged molecules are not very soluble in lipids and therefore have low membrane permeability

Answer 15

Neutral molecules (e.g. gases such as carbon dioxide and oxygen) have a high permeability.

Answer 16

Although water is a charged molecule, membranes are highly permeable to it. Water moves through special tiny hydrophilic pores in the membrane by the process of osmosis.

Answer 17

Molecules that have low permeability rely on carrier proteins to transport them across membrane in cells. This is known as active transport.

Answer 18

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

Answer 19

a phenomenon whereby a single-celled organism resides within another cell as part of a mutually beneficial relationship

Answer 20

The ocular lens is 10X magnification, so if the objective lens is 40X the total magnification = 10*40 = 400X

Answer 21

Passive transport describes the movement of particles from an area where they are in high concentration to an area where they are in low concentration. It does not require energy

Answer 22

diffusion and osmosis

Answer 23

Osmosis is the movement of water across a semi-permeable membrane

Answer 24

is the movement of any molecules along a concentration gradient, such as when a drop of food dye is placed water

Answer 25

``` ATP Adenosine Triphosphate (ATP) ```

Answer 26

cell membrane serves to protect the cell from undesirable external conditions and controls the movement of substances into and out of the cell (including wastes). The cell membrane must also be flexible to allow the cell to contract and expand as the cell’s contents change.

Answer 27

The basicchemical unit is a “phospholipid” molecule; a lipid (fat) with phosphate groups attached. Each molecule has two distinct ends; one which is attracted to water molecules (“hydrophilic”) and the other is repelled by water (“hydrophobic”).

Answer 28

"to like" | heads

Answer 29

'hate/fear" | tails

Answer 30

Two layers of phospholipids form each membrane. The molecules cling to each other, and line up with their hydrophilic ends outwards. The water-loving ends are attracted to the watery environment both inside and outside the cell.The hydrophobic ends are repelled from the watery surroundings, and cling together inside the membrane itself.

Answer 31

mostly proteins- with carbohydrates attached

Answer 32

“receptors” for messenger chemicals. • identification markers, so your body knows its own cells from any foreign invaders. • to help chemicals get through the membrane.

Answer 33

a liquid structure and the different molecules embedded within it are like the different shapes & colours in a “mosaic” tile pattern.

Answer 34

simple diffusion refers to the process of movement of particles across a semipermeable membrane naturally.

Answer 35

・ Concentration (the greater the gradient, the faster the diffusion) ・ Temperature (the higher the temperature, the faster the diffusion) ・ Particle size (the smaller the particle size, the faster the diffusion)

Answer 36

The protein channels in the cell membrane allow for the movement of particles. The process occurs when particles move down the concentration gradient. Ø Transport proteins are more specific about what particles are transported Ø Transport is more rapid than simple diffusion Ø Transport proteins can become saturated as the concentration increases

Answer 37

Channel proteins are found in membranes and are specific for substances. They do not bind with the molecules and open and close to allow specific molecules to be transported.

Answer 38

Carrier proteins bind the molecules being transported.

Answer 39

1 In all living things, diffusion is used in transporting lipids waste products and other substances in and out of cells. 2. In a living cell, when oxygen is used up in respiration, the oxygen level is lowered. The concentration of oxygen becomes lower than the surrounding (outside the cell) so oxygen will diffuse into the cell through the cell membrane. 3. When living cells produce carbon dioxide as a waste product, the surrounding concentration is lowered and so the carbon dioxide will diffuse out of the cell into the surroundings. 4. When cells in green leaves photosynthesis, they use up carbon dioxide and produce oxygen.

Answer 40

Movement of water into a cell occurs when there is a higher concentration of water molecules on the outside of the cell than inside the cell.

Answer 41

If it is dry outside the cell, water will diffuse out. Water molecules will also diffuse into a cell if there is a high concentration of chemicals inside it compared to the outside. If there is a greater concentration of solutes outside the cell, water will move out through the membrane.

Answer 42

This process occurs through a semipermeable membrane. Cell membranes are permeable to water. Water will continue to enter the cell until the osmotic gradient is equal.

Answer 43

equal concentrations of solutes | will remain the same

Answer 44

have a higher concentration of solute | will shrink in size

Answer 45

have a lower concentration of solute | will grow in size

Answer 46

When red blood cells are in a hypertonic (higher concentration) solution, water flows out of the cell faster than it comes in. This results in crenation (shriveling) of the blood cell. On the other extreme, a red blood cell that is hypotonic (lower concentration outside the cell) will result in more water flowing into the cell than out. This results in swelling of the cell and potential hemolysis (bursting) of the cell. In an isotonic solution, the flow of water in and out of the cell is happening at the same rate.

Answer 47

A process resulting from osmosis in which red blood cells, in a hypertonic solution, undergo shrinkage and acquire a notched or scalloped surface.

Answer 48

bursting of the blood cell

Answer 49

The cells take in materials in bulk by forming new vesicles from the cell membrane. Materials near the cell membrane are enclosed by the membrane, which then forms a vesicle. The vesicle transports the substance to its required location in the cell.

Answer 50

The secretory vesicle membrane and cell membrane touch, some proteins alter the arrangement of the phospholipids. The membranes fuse, and the contents of the secretory vesicle are released from the cell/ The vesicle membrane becomes a permanent part of the cell membrane.

Answer 51

Exocytosis secretes protein, as well as cellular water and the breakdown of products from lysosomes.

Answer 52

Ø As the size increases, the surface area to volume ratio decreases. Ø Smaller cells can exchange matter more efficiently.

Answer 53

The surface area of the cell membrane affects the rate of exchange between the cell and its environment. Larger cells have greater metabolic needs, so need to exchange more materials.

Answer 54

Cell compartmentalisation allows organelles to have the right conditions and concentrations of enzymes and reactants. It reduces the amount of exchange that needs to occur across the membrane. It creates more space for membrane bound enzymes, which increases cell activity. Cell membrane extensions occur in cells that are involved in absorbing nutrients or secreting wastes. By extending the membrane, it counteracts the surface area to volume problems these cells have. A flattened shape will keep the volume constant, which allows for a larger surface area. It also reduces the distance that substances need to be transported to and from the membrane.

Answer 55

The greater the surface area the larger the amount of raw material that can enter at only one time. BUT each unit of volume requires a specific amount of surface area to supply its metabolize with raw materials (all the way to the middle of the cell, the nucleus). If a cell’s volume is too large the organelles in the center are too far away for diffusion of nutrients to effectively occur.

Answer 56

Autotrophs (self-feeders) make their own organic compounds from inorganic compounds found in soil and atmosphere. This process is called carbon fixation. They are known as producers and include plants that carry out photosynthesis.

Answer 57

Heterotrophs (other-feeders) gain organic compounds by consuming other organisms. They are known as consumers and include animals and fungi.

Answer 58

The elements found on Earth are found in all types of cells, both living and nonliving. These atoms are organised into larger compounds in living things.

Answer 59

oxygen water nitrogen carbon dioxide

Answer 60

Water (H2O) is a solvent and transport medium. Chemical reactions in cells take place in a water-based fluid (cytosol).

Answer 61

Oxygen (O2) is needed for energy and is achieved through cellular respiration. Terrestrial organisms take it in by gas, and aquatic organisms take it in solution.

Answer 62

Carbon dioxide (CO2) is the best source of carbon atoms for organic molecules. It is taken into plant leaves in gas, is converted into sugars and returns to the atmosphere (photosynthesis).

Answer 63

Nitrogen (N) is part of amino acids that link to form protein molecules. Consumers get their Nitrogen from plants that are added to the soil from the N2(g) in the air.

Answer 64

Calcium (bones and teeth) ・ Sodium and Potassium (nervous system) ・ Magnesium (muscle function) ・ Iron (haemoglobin production)

Answer 65

lipids carbohydrates proteins Nucleic acids

Answer 66

Nucleic acids carry genetic information. The two types are DNA and RNA, which are made of long chains of nucleotides, sugars and phosphates. ・ DNA carries information required to assemble proteins from amino acids ・ RNA helps with the manufacturing of proteins in the cells

Answer 67

Lipids are important in cell membranes. They are good for energy storage and help maintain structure of the membrane.

Answer 68

Proteins are composed of amino acids. They have many functions including enzymes, hormones, antibodies or carrier molecules (haemoglobin). Proteins are a part of the cell membrane.

Answer 69

``` Carbohydrates are important for energy and structure of organisms. Glucose Sucrose Starch Cellulose ```

Answer 70

Autotrophs and heterotrophs have waste products from their metabolisms which are not useful which are known as excretion. → Carbon dioxide from cellular respiration → Nitrogenous wastes from the breakdown of proteins and nucleic acids Passive involves osmosis and diffusion. Active is when toxins and ions are being removed against their concentration gradient (endocytosis and exocytosis).

Answer 71

Carbon dioxide + water = glucose + Oxygen

Answer 72

When plants have light, water (H2O) and Carbon dioxide (CO2) and together make glucose (C6H12O6) produced in their green tissues, usually leaves. They trap the energy from the sun and convert it into chemical energy, which is stored in the bonds between the glucose molecules.

Answer 73

Firstly it is the reaction which transforms radiant heat from the sun into chemical energy in organisms. Autotrophs therefore begin food chains where energy is passed from one trophic level to the next trophic level. Secondly photosynthesis releases gaseous oxygen and removes carbon dioxide from the atmosphere.

Answer 74

They are the site of photosynthesis. This is where the light energy is converted into food (glucose) and Oxygen is released. The leaves, and sometimes stems, are green because of the chlorophyll pigment. Chlorophyll absorbs the light energy. In vascular plants. Chloroplasts are found in the mesophyll, which is at the upper surface of the leaf, meaning more sun exposure. This increases the rate of photosynthesis. Inside each chloroplast are flattened membranes, called grana. The grana holds the thylakoids, where chlorophyll is made.

Answer 75

Chlorophyll captures solar energy and uses it to produce ATP. Water is then split into Hydrogen ions and Oxygen gas. These reactions take place in the grana, where chlorophyll is located. Water = Hydrogen ions + Oxygen + ATP Note: = light and chlorophyll

Answer 76

They produce glucose, water and ADP. These reactions do not require solar energy. ATP from stage 1 provides the energy for stage 2. This energy allows Carbon dioxide and Hydrogen ions to form glucose and water. These reactions take place in the stroma. Glucose + Water + ADP = Hydrogen ions + ATP + Carbon dioxide

Answer 77

Light intensity: when there is a little light, the light dependant reactions cannot occur 2. Carbon dioxide concentration: when there is little Carbon dioxide, photosynthesis cannot occur 3. Temperature: all reactions are catalysed by enzymes, and if temperatures become too extreme, the enzymes could denature and therefore photosynthesis could not take place

Answer 78

Cellular respiration is a chemical reaction that occurs in living cells. It uses glucose and oxygen to produce unstable energy, with Carbon dioxide as a waste.

Answer 79

ATP is the immediate source of energy for cells. The unstable energy of ATP is contained in the phosphate bonds. The cycling of ATP and ADP means energy is always available.

Answer 80

・ Carbon dioxide ・ Water ・ Energy

Answer 81

The first main stage is glycolysis. This is when the glucose molecules split into two parts and do not require oxygen. The second main stage is aerobic respiration (Oxygen is present) or anaerobic respiration (if Oxygen is absent). In a living cell, anaerobic respiration occurs if there’s insufficient Oxygen, but aerobic happens all the time.

Answer 82

Enzymes are known as catalysts of chemical reactions – they allow reactions to speed up and to take place with less energy. Many reactions would not take place without them . · Enzymes are proteins that are rounded in shape. · Enzymes are very important to cells because they help molecules to form, to breakdown, or to exchange parts

Answer 83

A chemical reaction takes place at the active site and the more complex molecule (substrate) is broken down into two simpler forms (products).

Answer 84

a more complex molecule

Answer 85

This takes place either inside the cell (intracellular enzyme i.e. respiration and photosynthesis) or outside the cell (extracellular enzyme i.e. the digestive enzymes)

Answer 86

The substrates bind to the active site where a chemical reaction takes place. The two less complex molecules are metabolized into a more complex molecule to be used within our bodies. The substrates are the reactants of the chemical reaction.

Answer 87

Substrate and enzyme work like a lock and key. | first model

Answer 88

But if the substrates don’t fit sometimes the enzyme can slightly alter its shape to accommodate the substrate. This is known as induced fit.

Answer 89

that is their shape is destroyed beyond repair and hence the substrate won’t bin

Answer 90

Inorganic cofactors are generally inorganic ions, whereas coenzymes are small, non-protein molecules, often used to carry substances to and from reactions. Coenzymes are particularly important in terms of metabolic pathways. cofactors activate some enzymes

Answer 91

as temperature increases, kinetic energy increases and there will be more collisions, which increases activity. However, above optimum temperature the enzyme denatures.

Answer 92

There are some enzymes that can work at very acidic or basic pH - but their activity will decrease as they get further away from their optimal pH. The pH affects the enzyme by causing changes to the bonds that give the enzyme its 3D tertiary structure. These are bonds such as ionic, disulphide and hydrogen bonds. As the pH moves away from the optimal pH, either becoming more acidic (lower pH) or more basic (higher pH), the bonds start to become disrupted and the shape of the enzyme changes. The enzyme is denatured.

Answer 93

Increasing substrate concentration also increases the rate of reaction to a certain point. Once all of the enzymes have bound, any substrate increase will have no effect on the rate of reaction, as the available enzymes will be saturated and working at their maximum rate. Increasing Substrate Concentration increases the rate of reaction. This is because more substrate molecules will be colliding with enzyme molecules, so more products will be formed. However, after a certain concentration, any increase will have no effect on the rate of reaction, since Substrate Concentration will no longer be the limiting factor. The enzymes will effectively become saturated, and will be working at their maximum possible rate.

Answer 94

1. Excretion – elimination of harmful and unwanted products of metabolism 2. Osmoregulation – control of body water and salt levels