Chapter Two - Origins of light

Question 1

Proteins

Answer 1

Molecules that carry out most of the activities of life, including the synthesis of all other biological molecules. A protein consists of one or more polypeptides depending on the protein.

Question 2

Cell Theory

Answer 2

Three generalizations yielded by microscopic observations: all organisms are composed of one or more cells; the cell is the smallest unit that has the properties of life; and cells arise only from the growth and division of pre-existing cells.

Question 3

Seven Characteristics of All Life Forms

Answer 3

1. Display order
2. Harness and utilize energy
3. Reproduce
4. Respond to stimuli
5. Exhibit homeostasis
6. Growth and Development
7. Evolve

Question 4

Reducing Atmosphere

Answer 4

No oxygen to partially bock UV light and abundant lightning provided the energy to make the building blocks of life, because of the presence of large concentrations of molecules such as hydrogen (H2), methane (CH4), and ammonia (NH3). The original atmosphere was a reducing atmosphere. These molecules are said to be fully reduced because they contain max number of electrons and hydrogen.

Question 5

Oxidizing Atmosphere

Answer 5

21% of oxygen is an oxidizing atmosphere. Presence of oxygen prevents complex, electron-rich molecules from being formed because oxygen is a strong oxidizing molecule.

Question 6

Miller-Urey Experiment

Answer 6

Tested theory on earliest substances formed. Placed hydrogen, methane, ammonia and water vapour in apparatus that was closed and exposed the gases to an energy source (continuously sparking electrodes). Water vapour was added to the “atmosphere” at one part of apparatus and subsequently condensed back into water by cooling in another part.

Question 7

Protobiont

Answer 7

The term given to a group of abiotically produced organic molecules that are surrounded by a membrane or membrane like structure.

Question 8

DNA

Answer 8

Deoxyribonucleic acid

The large, double-stranded, helical molecule that contains the genetic material of all living organisms.

Question 9

RNA

Answer 9

Ribonucleic acid
A polymer assembled from repeating nucleotide monomers in which the five carbon sugar is ribose. Cellular RNAs are mRNA (which is translated to produce a polypeptide), tRNA (which brings an amino acid to the ribosome for assembly into a polypeptide during translation), and RNA (which is structural component of ribosomes). The genetic material of some viruses is RNA.

Question 10

Ribozymes

Answer 10

An RNA-based catalyst that is part of the biochemical machinery of all cells.

Question 11

Ribosomes

Answer 11

A ribonucleoprotein particle that carries out protein synthesis by translating mRNA into chains of amino acids.

Question 12

ATP

Answer 12

Adenosine Triphosphate

The primary agent that couples exergonic and endogenic reactions.

Question 13

RNA World

Answer 13

Theory that early life may have existed with a single molecule being a carrier of information and biological catalyst. The molecule carried information in its nucleotide sequence and is a catalyst because of the molecules ability to form 3-D shapes. This is RNA and is self-replicating.

Question 14

Basic steps of creating life

Answer 14

1. the abiotic (non-living) synthesis of organic molecules such as amino acids.
2. the assembly of complex organic molecules from single molecules, including proteins, RNA, or both.
3. the aggregation of complex organic molecules inside membrane-bound protobionts.

Question 15

L1 Ligase Ribozyme

Answer 15

Synthetic ribozyme that has been shown to catalyse the joining of two RNA monomers together. This shows that a ribozyme may have existed in primitive earth capable of ligating nucleotides together making RNA able to replicate.

Question 16

ADP

Answer 16

Adenosine Diphosphate
A nucleotide composed of adenosine and two phosphate groups that is formed in living cells as an intermediate between ATP and AMP and that is reversibly converted to ATP for the storing of energy by the addition of a high-energy phosphate group.

Question 17

Stromatolites

Answer 17

Fossilized remains of ancient cyanobacterial mats that carried out photosynthesis by the water-splitting reaction.

Question 18

Panspermia Hypothesis

Answer 18

Very simple forms of life are present in outer space and many have seeded early earth.

Question 19

Prokaryotes

Answer 19

Organism in which the DNA is suspended in the cell interior without separation from other cellular components by a discrete membrane.

Question 20

Eukaryotes

Answer 20

Organism in which the DNA is enclosed in a nucleus.

Question 21

Mitochondria

Answer 21

Membrane-bound organelle responsible for synthesis of most of the ATP in eukaryotic cells.

Question 22

Chloroplasts

Answer 22

The site of photosynthesis in plant cells.

Question 23

Nucleus

Answer 23

The central region of eukaryotic cells, separated by membranes from the surrounding cytoplasm, where DNA replication and messenger RNA transcription occur.

Question 24

Nucleoid

Answer 24

The central region of prokaryotic cells with no boundary membrane separating it from the cytoplasm, where DNA replication and messenger RNA transcription occur.

Question 25

Chromosome

Answer 25

The nuclear unit of genetic information, consisting of a DNA molecule and associated proteins.

Question 26

Vesicles

Answer 26

A small, membrane-bound compartment that transfers substances between parts of the endomembrane system.

Question 27

Endoplasmic Reticulum (ER)

Answer 27

In eukaryotes, an extensive interconnected network of cisternae that is responsible for the synthesis, transport, and initial modification of proteins and lipids.

Question 28

Golgi Complex

Answer 28

In eukaryotes, the organelles responsible for the final modification, sorting, and distribution of proteins and lipids.

Question 29

Exocytosis

Answer 29

In eukaryotes, the process by which a secretory vesicle fuses with the plasma membrane and releases the vesicle contents to the exterior.

Question 30

Endocytosis

Answer 30

In eukaryotes, the process by which molecules are brought into the cell from the exterior involving a bulging in of the plasma membrane that pinches off to from an endocytic vesicle.

Question 31

Endomembrane System (endo = within)

Answer 31

In eukaryotes, a collection of interrelated internal membranous sacs that divide a cell into functional and structural compartments.

Question 32

Theory of Endosymbiosis

Answer 32

Suggests mitochondria and chloroplasts evolved from ingested prokaryotes. The proposal that the membranous organelles of eukaryotic cells (mitochondria and chloroplasts) may have originated from symbiotic relationships between two prokaryotic cells.

Question 33

Evidence to Support the Theory of Endosymbiosis

Answer 33

1. Morphology - shape of both mitochondria and chloroplasts are similar to aerobic prokaryotes and photosynthetic cyanobacteria.
2. Reproduction - divide by binary fission which is how prokaryotic cells divide.
3. Genetic Information - both contain DNA (small amounts) which is the same as free-living cells.
4. Transcription and Translation - both contain transcription and translation machinery (ribosomes) which are similar to prokaryotes.
5. Electron Transport - can generate ATP through their own electron transport chains just like free-living prokaryotes.

Question 34

Cytoskeleton

Answer 34

The interconnected system of protein fibres and tubes that extends throughout the cytoplasm of a eukaryotic cell.

Question 35

Microtubule

Answer 35

A cytoskeletal component formed by the polymerization of tubulin into rigid, hollow rods about 25nm in diameter.

Question 36

Intermediate Filament

Answer 36

A cytoskeletal filament about 10 nm in diameter that provides mechanical strength to cells in tissues.

Question 37

Microfilament

Answer 37

A cytoskeletal filament composed of actin.

Question 38

Flagella (flagellum)

Answer 38

A long, threadlike, cellular appendage responsible for movement; found in both prokaryotes and eukaryotes, but with different structures and modes of locomotion.

Question 39

9 + 2 Complex

Answer 39

Eukaryotic flagellum or cilium. In the bundle, a circle of nine double microtubules surrounds a central pair of single microtubules, forming what is known as the 9 + 2 complex. Dynein motor proteins slide the microtubules of the 9 + 2 complex over each other to produce the flagellar or ciliar movements.