Cells and the Molecules of Life (MOL100 - Lecture 1)

Flashcards covering the essential concepts from the lecture on 'Cells and the Molecules of Life', including macromolecules, cell types, organelles, cellular processes, and cell connections.

What are the four main (macro-) molecules of life?

Proteins, Nucleic acids, Phospholipids, and (Saccharides)

What are the two fundamental units of life based on cell type?

Prokaryotic cells and Eukaryotic cells

Name three model organisms used in molecular biology.

E.coli, yeast, C.elegans, Drosophila, zebrafish, mouse, Arabidopsis thaliana (any three are acceptable)

Why can "simple" organisms like bacteria or yeast be used to learn about molecular biology?

Because all living organisms descended from a common ancestral cell and share many fundamental features and "Molecules of life".

What are proteins made of?

Chains of amino acids

How many different amino acids are there?

20

What determines the 3-dimensional structure of proteins?

The sequence (order) of amino acids

What is one key function of proteins related to chemical reactions?

They can act as enzymes, catalyzing chemical reactions.

What is an example of a structural protein?

Filaments of the cytoskeleton

What are the four different nucleotides that DNA consists of?

A, G, T, and C

How do the two DNA strands bind in a double helix?

A always binds to T, and C always binds to G (complementary binding).

Why is the complementarity of DNA strands essential for heredity?

It allows for making copies of the DNA.

What is the process where DNA is transcribed into RNA?

Transcription

What happens to messenger RNAs (mRNAs)?

They are translated into proteins.

What are genes?

Functional units of the DNA strand that encode information for proteins.

What does it mean for phospholipids to be amphipathic molecules?

They have a hydrophilic ("water-loving") head and a hydrophobic ("water-fearing") tail.

How do phospholipids arrange themselves in aqueous liquids?

They form bilayered (two-layered) membranes with hydrophilic heads facing outwards and hydrophobic tails facing inwards.

What is the function of biomembranes?

To surround aqueous liquids, separating the inside of cells from the environment and generating compartments in cells.

What are organelles?

Membrane-surrounded compartments in eukaryotic cells specialized for different functions.

What is the cytoplasm?

The content of a cell except the nucleus.

What is the cytosol?

The aqueous part of the cytoplasm, after removal of the organelles.

What defines eukaryotic cells?

The presence of a nucleus.

What is chromatin composed of in eukaryotic cells?

DNA wrapped around proteins called histones.

How is chromatin organized in eukaryotic cells?

In linear pieces called chromosomes.

What encloses the nucleus?

The nuclear envelope, consisting of an inner and an outer membrane.

What allows the exchange of molecules between the nucleus and cytoplasm?

Nuclear pores.

What is the function of the smooth ER?

It is the site of lipid biosynthesis.

What distinguishes the rough ER from the smooth ER?

The rough ER has ribosomes on its surface.

What is the function of ribosomes?

They translate mRNAs into proteins.

Are ribosomes membrane-bound organelles?

No, they are specialized cellular structures not surrounded by a membrane.

What is the function of the Golgi apparatus?

It modifies proteins and lipids received from the ER and sorts them into transport vesicles.

What is the function of lysosomes?

They are digestive organelles containing enzymes that degrade macromolecules.

In what conditions do lysosomal enzymes work best?

Acidic conditions.

What is the primary function of mitochondria?

They use nutrients to generate ATP through a process called cellular respiration.

In what organisms are chloroplasts found?

Plants and algae.

What process do chloroplasts carry out?

Photosynthesis, converting CO2 and H2O into sugars and O2.

What is the cytoskeleton?

A network of different types of long filaments (fibres) that extend throughout the cytoplasm.

Name the three main types of filaments in the cytoskeleton.

Microtubules, actin filaments, and intermediate filaments.

What are the functions of the cytoskeleton?

It organizes the cell, keeps organelles in place, and serves as rails for transport.

What is the function of tight junctions in a sheet of cells?

They prevent the leakage of fluid between cells and limit the movement of proteins in the cell membrane.

What do anchoring junctions do?

They bridge the cytoskeleton of neighboring cells.

What are gap junctions?

Small channels that allow the exchange of small molecules and electric current between cells.

What are the four phases of the eukaryotic cell cycle?

Gap phase 1 (G1), synthesis phase (S), gap phase 2 (G2), and mitosis (M).

What happens during the S phase of the cell cycle?

The cell replicates its DNA (hereditary information).

In which phase do cells typically rest if they stop dividing?

G0 phase

What two domains constitute the Prokaryota?

Bacteria and Archaea

What distinguishes prokaryotic cells from eukaryotic cells regarding their nucleus?

Prokaryotic cells have no nucleus.

Where is the main genetic material found in prokaryotic cells?

As a circular DNA molecule in the nucleoid.

Do prokaryotic cells have membrane-bound organelles?

No.

Name one difference between Bacteria and Archaea.

Cell membranes of Archaea are different from bacteria and eukaryotes; transcription and translation machinery of Archaea is more similar to eukaryotes; many genes from Archaea are found in eukaryotes but not bacteria. (Any one is acceptable.)

In what kind of environments do Archaea often live?

Extreme environments like high temperature, high salt concentrations, or very acidic environments.

Why can bacteria be used as model organisms for molecular biology despite differences in cellular organization?

Many cellular and molecular processes are highly conserved (highly similar) between prokaryotes and eukaryotes.