1.5 the origin of cells

Question 1

when was this theory created: “cells can only be produced by the division of a pre-existing cell”?

Answer 1

1880s

Question 2

what is the name of the first cell produced by the fusion of a sperm and egg cell?

Answer 2

zygote

Question 3

is the creation of an entirely new cell possible?

Answer 3

no

Question 4

definition of a spontaneous generation

Answer 4

the formation of a living organism from a non-living organism

Question 5

who was the scientist who produced an experiment to discard this theory

Answer 5

Louis Pasteur

Question 6

give me 3 reasons why spontaneous generations don’t exist

Answer 6

1) cells have complex structures and no natural mechanism can produce them from simpler subunits
2) there is no example of the increasing population without cell division occurring
3) viruses are produced in simple subunits but don’t consist of cells

Question 7

what did Pasteur conclude?

Answer 7

that fungi appeared in the unboiled broth through the air passing but there was no spontaneous generation. Which discards the theory because it stated that the air was the cause of this phenomenon

Question 8

how many stages did living cells evolve into?

Answer 8

4

Question 9

explain the main stages of cells evolving

Answer 9

1) Production of carbon compounds for example sugars or amino acids
2) Assembly of carbon compounds into polymers
3) Formation of membranes
4) Development of a mechanism for inheritance

Question 10

definition of the endosymbiosis theory

Answer 10

it states that mitochondria were once free-living prokaryotic organisms that had developed the process of aerobic cell respiration

Question 11

what type of relationship did smaller and larger prokaryotic cells have?

Answer 11

mutualistic relationship–> were both benefited from each other

Question 12

what type of role did the smaller cell have inside the larger cell? ( endosymbiosis)

Answer 12

It was able to supply energy through aerobic respiration to the larger cell

Question 13

what type of role did the larger cell have? ( endosymbiosis)

Answer 13

it supplied food to the smaller one

Question 14

explain the origin of chloroplasts

Answer 14

If prokaryote developed photosynthesis it then got taken by a larger cell. After it could have developed into chloroplasts of photosynthetic eukaryotes

Question 15

what are 4 features of mitochondria and chloroplasts that suggest that evolution took place?

Answer 15

1) they have their own genes on a circular DNA molecule
2) they have their own 70S ribosomes
3) they transcribe DNA and use Rna to synthesize proteins
4) they are only produced by division of pre-existing mitochondria and chloroplast

Question 16

definition of bilayer

Answer 16

a film or membrane with two molecular layers

Question 17

definition of polymer

Answer 17

a substance that has a molecular structure built up chiefly or completely from a large number of similar units bonded together, e.g. many synthetic organic materials used as plastics and resins

Question 18

definition of endocytosis

Answer 18

Endocytosis is the process by which cells take in substances from outside of the cell by engulfing them in a vesicle.

Question 19

explain 1) Production of carbon compounds for example sugars or amino acids (cell evolution stages)

Answer 19

Miller and Riley passed steam through a mixture of hydrogen, methane and ammonia, which represented the atmosphere of the Earth. They also used electrical discharges to represent lightning. And found out that amino acids and there compounds were formed

Question 20

explain 2) Assembly of carbon compounds into polymers (cell evolution stages)

Answer 20

using deep-sea vents: “ cracks in the Earth’s surface gushing hot water containing inorganic chemicals such as iron sulfide”, to supply energy. Which can be used to assemble carbon compounds into polymers

Question 21

explain 3) Formation of membranes (cell evolution stages)

Answer 21

Carbon compounds are firstly naturally assembled into bilayers. These form vesicles resembling plasma membranes of cells. Therefore they allow internal chemistry to develop

Question 22

explain 4) Development of a mechanism for inheritance ( cell evolution stages)

Answer 22

living organisms have genes and enzymes that act as catalysts. To replicate they need enzymes that are made by genes. Instead, they found a solution. Using Rna they are able to store info, self-replicate and can act as a catalyst

Question 23

how can we trace the origin of our cells?

Answer 23

by looking at the zygote that is the fusion of our mother and father. this allows us to go back to our ancestors

Question 24

who were three important people who discovered anomalies which could suggest spontaneous generation?

Answer 24

Theophrastus Aristotele and Paracelsus

Question 25

why did the idea of spontaneous generation persist?

Answer 25

microorganisms weren’t discovered and sexual reproduction wasn’t understood