BABS1201 Lecture 1: 1. Life

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rubysalmon926

28 May 2018

School

UNSW, UNSW Sydney

Department

Biotechnology & Biomolecular Sciences

Course

BABS1201

Professor

All

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Life

Learning outcomes

• Describe some properties of water that make it essential for life as we know it

• List the characteristics of life

• List the major elements of life

• Define what a cell is

• Explain how the diversity of life is classified

• Compare and contrast prokaryotes and eukaryotes

Most abundant elements

• Hydrogen

• Helium

• Oxygen

• Carbon

Water

Why is water needed for life?

• Nearly all biological molecules assume their shapes and functions in response to the physical

and chemical properties of water

• Medium for most biochemical reactions

• Reactions involving water comprise many of those that support life (photosynthesis)

• Living organisms are found where water is found

Molecular structure

• Two hydrogen covalently bonded to one oxygen

• Oxygen = more electronegative

o Electronegative - the atom has a greater capacity to draw electrons to it

• Polar molecule, the electrons are unequally shared - overall charge is unevenly distributed

o Oxygen end is slightly negative

o Hydrogen end is slightly positive

Polar molecule - has a net dipole as a result of opposing charges, polar bonds are arranged

asymmetrically

• Water can be ionised:

•

Cohesion

• Water molecules attract each other

•

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o Force of hydrogen bonds between bonds > force of gravity

Tension

• Water molecules near surface interact more with those below and adjacent to them

• Causes the surface to be film-like, can support some weight

o Water tension in the linings of the lungs can cause breathing difficulties for premature

babies, oxygen can not be absorbed efficiently

Universal solvent

Dissolves:

• Salts, sugars, acids, alkalis, gases

Fats and oils

• Fats and oils are hydrophobic - are not charged and are not attracted to water

• They do not mix, hence are not dissolved in water

Soaps

• Have both hydrophobic and hydrophilic ends.

• Hydrophobic end attracts fats through dispersion forces

• Hydrophilic end attracts water through dipole-dipole bonds

•

High Specific Heat Capacity

• High boiling temperature

• Heat dissipated through perspiration

Water expands and floats when it freezes

• Solid water: forms a lattice, creating holes and more space between molecules than in liquid

• Compatible with aquatic life

o Water freezes from the surface, allowing aquatic life to continue underneath the ice

o If water were to sink, the oceans with freeze from the bottom upwards, causing fish to

be forced to the surface

Hydration/dehydration reactions

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Document Summary

Most abundant elements: hydrogen, helium, oxygen, carbon. Living organisms are found where water is found. Polar molecule - has a net dipole as a result of opposing charges, polar bonds are arranged asymmetrically: water can be ionised: Cohesion: water molecules attract each other, force of hydrogen bonds between bonds > force of gravity. Fats and oils are hydrophobic - are not charged and are not attracted to water: they do not mix, hence are not dissolved in water. Soaps: have both hydrophobic and hydrophilic ends, hydrophobic end attracts fats through dispersion forces, hydrophilic end attracts water through dipole-dipole bonds. High specific heat capacity: high boiling temperature, heat dissipated through perspiration. Solid water: forms a lattice, creating holes and more space between molecules than in liquid: compatible with aquatic life, water freezes from the surface, allowing aquatic life to continue underneath the ice.

Related Questions

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.

Lysosomes

Endosomes

Peroxisomes

Nucleosomes

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies?

rapid rate of reproduction

all of the above

ability to grow under controlled conditions

amenability to genetic manipulation

By definition, prokaryotic cells do not possess __________.

ribosomes.

a nucleus.

membrane bilayers.

replication machinery.

Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the __________ of light.

intensity

absorption

wavelength

filtering

Choose the phrase that best completes this sentence: Microtubules ____________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.

generate contractile forces

can rapidly reorganize

are found in especially large numbers in muscle cells

are intermediate in thickness

Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?

cell division

cell motility

vesicle transport

membrane support

DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA?

It contains thymine.

It has 5'-to-3' directionality.

It is single-stranded.

It contains uracil.

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also limit the geometry of the molecule because they ____________________.

prevent additional bonds from being formed with the bonded atoms.

limit the rotation of the bonded atoms.

create a new arrangement of electron shells.

change the reactivity of the bonded atoms.

Drosophila melanogaster is a/an __________. This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model.

mammal

amphibian

bird

insect

10.

If the isotope 32S has 16 protons and 16 neutrons, how many protons, neutrons, and electrons will the isotope 35S have, respectively?

16, 19, 17

16, 19, 15

16, 19, 16

16, 20, 15

11.

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit?

cell

organelle

protein

DNA

12.

Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable?

the concentration of each molecule

the size of each molecule

surface complementarity between molecules

the rate of synthesis

13.

Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular level in bacteria. Which bacterial species had a central role in advancing the field of molecular biology?

E. coli

S. pombe

C. elegans

D. melanogaster

14.

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets. What is the lipid most commonly found in these droplets?

cholesterol

isoprene

triacylglycerol

palmitic acid

15.

Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are __________________.

anaerobes.

viruses.

parasites.

endosymbionts.

16.

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of material âburnedâ and the form of energy produced during cellular respiration?

17.

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?

BABS1201 Lecture 1: 1. Life

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