A2 Unity ad Diversity : Cells

Question 1

organic molecules

Answer 1

Molecules that contain carbon and hydrogen. Most biological molecules, including proteins, carbohydrates, lipids and nucleic acids are organic molecules.

Question 2

Metabolism

Answer 2

Chemical reactions that take place within the cell(s) of an organism.

Question 3

Homeostasis

Answer 3

The maintenance of constant internal conditions, despite changes in their external environments

Question 4

Miller–Urey hypothesis

Answer 4

spontaneous generation of simple organic molecules such as amino acids, carbohydrates and lipids occurred in the conditions on pre-biotic Earth.

Question 5

The ‘metabolism first’ hypothesis

Answer 5

life began with simple metabolic reactions that led to the formation of simple metabolic pathways, which then formed more complex molecules which formed the basis of cells.

Question 6

The ‘lipid world’ hypothesis

Answer 6

lipid bilayers evolved before RNA, providing a protective layer to encapsulate the RNA.

Question 7

endosymbiosis

Answer 7

A theory that eukaryotic cells evolved by engulfing and incorporating prokaryotic cells, which then became organelles within the eukaryotic cell.

Question 8

horizontal gene transfer

Answer 8

The exchange of genetic material between individuals that does not involve reproduction.

Question 9

stromatolites

Answer 9

Fossils formed by microorganisms.

Question 10

hydrothermal vents

Answer 10

Openings in the ocean bed where hot water, rich in minerals, is released into the oceans.

Question 11

anaerobic

Answer 11

Describes conditions in which air or oxygen is absent.

Question 12

autotroph

Answer 12

Convert abiotic sources of energy into energy stored in organic compounds,

Question 13

light microscope

Answer 13

A microscope that uses light to view specimens, usually with a magnification of 400–1500 times.

Question 14

micrometers (μm)

Answer 14

one thousandth of millimetre
or
one millionth of a meter
usually used to measure cells

Question 15

nanometer (nm)

Answer 15

one millionth of a millimetre
or
one billionth of a metre
usually used to measure proteins and viruses

Question 16

magnification equation

Answer 16

mag = image size / actual size

Question 17

electron microscope

Answer 17

Instrument using a beam of electrons to obtain a magnified image of a very small object such as a sub-cellular structure.

Question 18

resolution

Answer 18

The shortest distance between two separate points in a microscope’s field of view that can still be distinguished as separate objects.

Question 19

Freeze fracture microscopy

Answer 19

Microscopy technique where sample frozen then broken into small pieces which are observed using an electron microscope to see the internal structure.

Question 20

Cryogenic electron microscopy

Answer 20

Microscopy technique where samples are frozen to cryogenic temperatures to fix the molecules which are viewed using electron microscope.

Question 21

Immunofluorescence

Answer 21

A microscopy technique that attaches a fluorescent tag to antibodies which bind to antigens on specimen using light microscopes

Question 22

florescent dyes

Answer 22

Dyes that attach to certain structures and appear as brightly coloured spots using light microscopes

Question 23

plasmid

Answer 23

Small circular DNA molecule, physically separate from chromosomal DNA, found in bacteria and some other microscopic organisms and can be transfered between them

Question 24

polysaccarides

Answer 24

A major class of biomolecules, composed of long chains of carbohydrate molecules.

Question 25

Pili

Answer 25

The hairlike protein filaments on the cell wall that help with cell adhesion and transferring of DNA between two cells in microorganisms.

Question 26

compartmentalisation

Answer 26

The idea that eukaryotic cells contain membrane-bound organelles, such as mitochondria and chloroplasts to have control over their own conditions.

Question 27

Smooth endoplasmic reticulum

Answer 27

A membrane organelle within the cytoplasm of eukaryotic cells which produces and stores liquids.

Question 28

Rough endoplasmic reticulum

Answer 28

A network of membranes within the cell that is studded with ribosomes, which are responsible for synthesising proteins.

Question 29

Golgi apparatus

Answer 29

A membrane-bound organelle that sorts, modifies and packages proteins and lipids for transport to other parts of the cell or for secretion out of the cell.

Question 30

Vacuole

Answer 30

Membrane-bound organelle that helps to maintain the osmotic balance of the cell.

Question 31

Cytoskeleton

Answer 31

A network of protein fibres that provides shape and allows for the movement of molecules around the cell.

Question 32

Centrioles

Answer 32

Cylindrical organelles that help to establish and organise the microtubules, playing an important role in cell division.

Question 33

Lysosomes

Answer 33

Membrane-bound bags of hydrolytic enzymes that break down and destroy biological molecules and old cellular organelles.

Question 34

Anucleate

Answer 34

A eukaryotic cell without a nucleus.

Question 35

Multinucleate

Answer 35

A eukaryotic cell containing more than one nucleus.

Question 36

Caspid

Answer 36

The protein shell of a virus that surrounds and protects the genetic material.

Question 37

receptor-mediated fusion

Answer 37

The process by which a virus binds to a receptor on a host cell membrane to fuse with the host cell membrane and enter the cell.

Question 38

lysogenic cycle

Answer 38

A viral reproductive cycle involving integration of the virus genome into the host cell genome.

Question 39

lytic cycle

Answer 39

A viral reproductive cycle involving rapid production of viral progeny which lyse and destroy the host cell.

Question 40

convergent evolution

Answer 40

Pattern of evolution where distantly related organisms evolve similar traits in response to environmental similarities.