Lecture 1 - Review

Question 1

1. Why is carbon the best element to use to construct organic molecules?

Answer 1

This is in part due to carbon’s ability to readily form bonds with other atoms (up to four per
atom), giving flexibility to the form and function that biomolecules can take, such as DNA
and RNA, which are essential for the defining characteristics of life: growth and replication.
(Long chains and rings)

Question 2

2. Which macromolecule is the main building block of molecular machines in cells?

Answer 2

Proteins.

Proteins are one of the most vital biological building blocks. Due to its considerably large size, it is considered a macromolecule. The structure of a protein mainly consists of multiple units of amino acids.

Ribosomes are the molecular machine of living cells designed for decoding mRNA-encoded
genetic information into protein. Being sophisticated machinery, both in design and function, the ribosome not only carries out protein synthesis but also coordinates several other ribosome-associated cellular processes.

Question 3

If the salt level is higher inside cells than outside, how will the levels be equalized?

Answer 3

If there is more salt in a cell than outside it, the water will move through the plasma membrane into the cell, causing it to increase in size, and swell up as the water fills the cell in. It is imperative to combine it with salt.

Up the concentration gradient (active transport) - requires ATP

Question 4

Which membranous organelle is where oxygen is used to drive aerobic cellular
respiration?

Answer 4

Aerobic cellular respiration (with oxygen) takes place in the cell’s mitochondria.

Question 5

Which non-membranous organelle is the site of translation?

Answer 5

The organelle that is the site of translation is the ribosome. Ribosomes are the non-membranous
cell organelles made of basic proteins and rRNA are concerned with protein synthesis. They
originate within the nucleus.

Question 6

Which non-membranous structure forms the cell’s skeleton?

Answer 6

The cytoskeleton is a network of protein fibres that provide structure and support for all cells.

Question 7

If DNA content in a cell is examined, when is it highest during the following phases: G1,
S, G2?

Answer 7

Highest during the G2 phase - Interval following DNA replication; cell prepares to divide

Question 8

During mitosis, when are chromosomes most likely to be arranged along the equatorial
plate?

Answer 8

Metaphase

o Chromosomes move to the middle of the cell and become aligned along the equatorial
plate

o Spindle microtubules attach to centromeres of the sister chromatids