Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Biology and the origin of life > Flashcards

Biology and the origin of life Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what is science?

A

Science is an attempt to understand the
world around us with a logical and
structured approach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is biology?

A

Biology is a subset of science that aims to

understand the living world, it is also known as “The Science of Life”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the scientific method?

A

Interpret results, Forming hypotheses
make new —-> (tentative explanation;
observations testable, falsifiable)
/ /
Test hypotheses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is Empiricism

A

knowledge should be
derived from experience and
sensory evidence, not innate ideas
and traditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the reoccurring themes in the study of life?

A 
- Organisation
» Molecule › Cell › Tissue › Organ › Organism › Population › Community ›
Ecosystem › Biosphere
- Information: DNA, the genetic material
- Energy and matter
» Use of energy, recycling of matter
- Interactions
» At every level of organisation
- Evolution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

why is evolution is the core theme of Biology?

A

Theory of Evolution provides a unifying concept that explains much of the
living world

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Details of evolution are often misunderstood, why?

A
  • Evolution is NOT goal oriented
  • Natural selection is NOT the only mechanism of change. Mutations, gene flow and genetic drift are also powerful evolutionary forces.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does theory mean?

A

A scientific Theory is a general, verifiable principle that explains many observations (“general law”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how long ago did earth form and what was the first period of the earth?

A

Earth formed ≈ 4.6 BYA (billion years ago)
First, 0.5 BYA was a period of intense
bombardment
» Moon formed 4.5 BYA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what was the initial atmosphere of earth?

A

The initial atmosphere of methane, hydrogen,

ammonia and water vapour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When did life first appear?

A

Life appears ≈ 4.2 BYA
» Simple prokaryotic cells (“proto-cells”), similar
to today’s bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the four main organic molecules

A

Amino acids → protein
» Nucleotides → nucleic acid
» Simple sugars → carbohydrate
» Fatty acids → lipid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are biological macromolecules?

A

Biological macromolecules are polymers of

small organic molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Abiogenesis?

A

The leading scientific hypothesis
» The conditions of the early Earth made it possible for life to spontaneously form from non-living material
» Inorganic molecules → small organic molecules →
macromolecules → proto-cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Step 1 of Abiogenesis?

A

Step 1 – Create organic molecules:

  • Organic molecules today can only be created by living organisms
  • Organic compounds degrade quickly in an oxygen-rich (“oxidising”) environment
  • Oparin & Haldane (1920s) - early earth had a reducing
    environment: very little oxygen, but plenty of hydrogen (H), methane (CH4), ammonia (NH3) and water vapour (H2O)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what proof is there that life could have formed on early earth?

A
  • Experiment in 1953 by Miller and Urey
  • Simulated early Earth conditions
    » Hydrogen (H)
    » Methane (CH4)
    » Ammonia (NH3)
    » Water vapour (H2O)
    » And energy!
  • Created several organic molecules,
    including amino acids - in just a couple
    of days!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is Step 2 of Abiogenesis?

A

Step 2 - Polymerisation
- Miller Urey proved organic molecules created
from inorganic compounds in early Earth environment
» Reducing atmosphere, high energy input
- In a liquid environment and with some energy input, this “primordial soup” of organic molecules self-assembles into more complex macromolecules
» Amino acids → proteins
» Nucleotides → nucleic acid, esp. RNA
» Fatty acids → lipid vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what must all living organisms be able to do?

A 
» Organise biological molecules on a higher level
» Access and use energy (metabolism)
» Grow
» Respond to their environment
» Reproduce (store and
retrieve biological information
to create copies)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What was the first genetic material on earth?

A

RNA, because it is able to encode information and

assume a variety of shapes determined by nucleotide sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is step 3 of Abiogenesis

A

Step 3 –A protective layer
- Phospholipids (type of fatty acid with phosphate
group) are amphipathic
- In water, they will form micelles and eventually
self-assemble into sacs called vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the simple recipe for life?

A
  • Step 1 – Provide enough energy and starting material to create small organic molecules
  • Step 2 – Join them into macromolecules
    » Pick the one that can self-replicate (eg, RNA)
  • Step 3 – Wrap it in a flexible package that provides stability (phospholipid membrane)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the Panspermia hypothesis?

A

Panspermia is the evolution theory that Life did not originate on Earth:
» Problem: Creation of single-stranded RNA requires
borate and molybdate, both of which were unlikely to be found on Earth … but were common on Mars
» Observation 1: Plenty of evidence of inter-planetary
exchange (eg meteorites)
» Observation 2: Organic compounds are present in
meteorites (eg Murchison meteorite)
» Hypothesis: Life started on Mars and came to Earth on a rock.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a Polymer?

A

A substance that has a molecular structure built up from a large number of similar units bonded together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How are polymers synthesises and broken down?

A

Synthesised by dehydration reaction

broken down by hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are Carbohydrates used for?

A

Fuel and building material

26
Q

What are Lipids used for?

A
  • (Not true polymers)
  • Various functions, mostly structural
  • Share a “dislike” for water (“hydrophobic”)
  • Various, but most biologically important:
    » Fat: glycerol with up to 3 fatty acids
    » Phospholipid: component of cell membrane
    » Steroids: membrane, hormone precursor
27
Q

What are proteins used for?

A

Wide range of structure and functions

28
Q

What are nucleic acids (DNA, RNA) used for?

A

Store genetic information

29
Q

what are the different kinds of proteins?

A

Enzymatic proteins: selective acceleration of chemical reactions
Defensive proteins: protection against diseases
Storage proteins: storage of amino acids
Transport Protein: transport of substances
Hormonal Protein: coordination of activities of organism
Receptor proteins: response of cell to chemical stimulus
Contractile and motor protein: movement
Structural protein: support

30
Q

what are ribosomes?

A
  • RNA capable of performing biological function

including self-replication

31
Q

Why are proteins better than just RNA?

A
  • RNA is only capable of limited shapes and the shape
    determines the function!
    Proteins (polymers of AA) produce much greater variety of shapes
    » Proteins thus replaced RNA over time as they are better at performing a much wider variety of biological functions
32
Q

what is the typical AA structure and how many AA’s make up all proteins?

A

R =20 AA’s make up al
H | O proteins
\ | //
N —- C —- C
/ | \
H H OH

33
Q

what kind of reaction links AA’s?

A

Dehydration reaction links C in carboxyl
group of one AA to N in amino group of
another

34
Q

How many AA’s make up a single protein (usually)

A

Proteins usually made up of 200-300 AA,
but some much smaller, and some larger
» eg titins can be up to ≈ 30,000 AA

35
Q

What are the four levels of protein structure?

A
  1. Primary structure: Linear polypeptide chain
  2. Secondary structure: α-helix and β-pleated sheets (due to hydrogen bonds)
  3. Tertiary structure: main 3D shape, formed by interactions b/w side chains
  4. Quaternary structure: interaction b/w protein sub-units
36
Q

What is the Primary structure of a protein?

A

Simply the linear sequence of AA, eg.
» The smallest functional polypeptide
glutathione: Cys-Gly-Glu
» Transthyretin, a transport protein →

37
Q

What is the secndary structure of a protein?

A

Segments of the polypeptide chain form coiled or folded patterns
due to hydrogen bonding within the peptide backbone

38
Q

What is the teriary structure of a protein?

A
  • Main 3D shape of the protein
  • Affected by interactions between side chain (the “R-group”)
    » Hydrophobic interactions: away from water and towards each other
    » Hydrogen bonding: b/w polar R groups
    » van der Waal forces: b/w non-polar R groups
    » Ionic bonding: b/w + and - charged R groups
    » Disulfide bridges: sulfur of cysteine R groups
39
Q

What are two examples of the tertiary structure of a protein?

A
  • Hemoglobin (alpha sub-unit)

- Proteinase K

40
Q

What is the Quaternary structure of a protein?

A
  • not all proteins require this

- Assembly of multiple sub-unit polypeptides

41
Q

What determines the function of a protein?

A

AA’s determine the primary, secondary and tertiary structures. Therefore, AA sequence of a protein is the primary determinant of its function

42
Q

What is a key factor in protein structure?

A

Structure depends on environmental conditions (pH, salt concentration, temperature)

43
Q

What is protein denaturation?

A

In extreme conditions, weak chemical bonds can break leading to unravelling of protein:

  • Loss of structure = loss of function
  • This is why a high fever is dangerous
  • Can sometimes be “renatured” when returned in normal condition (not always – eg, egg protein)
44
Q

What are the Nucleic Acids?

A
  • DNA: Deoxyribonucleic acid
    » Encodes all information needed to create life’s diversity
  • RNA: Ribonucleic acid
    » Has several roles, but most basic is to deliver information from DNA to sites of protein synthesis
45
Q

What are the nucleotide bases?

A

» DNA: C, T, A, G

» RNA: C, U, A, G

46
Q

What is polynucleotide?

A

when nucleic acid molecules bond together and form a chain

47
Q

Who were Watson and Crick and what did they discover?

A

Watson and Crick using crystallography by
Rosalin Franklin, determined in 1953 that
DNA is formed by two intertwined strands
of nucleic acids: the DNA double helix

48
Q

What is the broad structure of a nucleotide?

A

Phosphate-sugar backbone on the outside, paired nitrogenous bases on the inside (purine-pyrimidine)

49
Q

What was Chargruff’s rule?

A

Chargraff’s rule (1950): if you analyse bases in DNA

of an organism, the percent A=T and percent G=C because A always pairs with T & G always pairs with C

50
Q

What is strand directionality?

A
  • In a double helix, there are two strands, 5’ to 3’ of one strand is opposite to the complementary strand, oriented in 3’ to 5’ direction.
  • Two complementary strands run in opposite directions (“antiparallel”)
51
Q

What is the role of DNA?

A

DNA carries hereditary information (the genetic code)

- Sequence of bases along DNA (and RNA) is unique for each gene

52
Q

How does DNA replication work?

A

Three steps of DNA replication
» Double helix unravels
» Free bases bond complementary bases on original “template” strands
» Polymerisation connects the bases together, forming two new “daughter” strands

53
Q

What is the difference between DNA & RNA?

A

RNA exists as single strands

» Pyrimidines: C, U (instead of T); Purines: A, G

54
Q

How does complimentary base pairing in RNA work?

A

Occurs either b/w two RNA molecules or b/w two stretches of same RNA molecule → various 3D structures → various functions

55
Q

What is mRNA?

A
  • DNA serves as a template for RNA synthesis

- RNA copies the message of DNA and transports it to site of protein production

56
Q

What are some roles of RNA?

A
  • Messenger RNA (mRNA) is linear, and carries message from DNA to protein assembly site
  • Protein assembly site: ribosome, a complex protein made up of ribosomal RNA (rRNA) and proteins, accepts the mRNA and produces the protein, with the help of …
  • Transfer RNA (tRNA): translate gene language into amino acid sequence
57
Q

What is a Codon

A

A nucleotide triplet, linked to specific amino acid

58
Q

What is the Central Dogma?

A

Explains the flow of genetic information within biological systems, proposed by Francis Crick in 1958

59
Q

What are viruses and what do they do?

A
  • Viruses are strands of nucleic acid (RNA or DNA) with a protein coat and lipid envelope
  • Viruses have evolved methods to reverse flow of information
    » RNA → DNA (“reverse transcription”)
    • Retroviruses (eg, HIV)
    » RNA → RNA (“RNA replication”)
    • Many RNA viruses replicate that way
60
Q

What are the benefits of biotechnology?

A
  • Understanding gene language can help us design specific proteins
  • By introducing specific genes into organisms (GMO), we can:
    » Develop high-yielding, disease resistant crops
    » Develop new techniques of waste remediation (eg, GM bacteria that consume oil)
    » Treat genetic diseases (“gene therapy”)

Biology (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions