A2.2.4 Structures common to cells in all living organisms

What is the function of DNA in living organisms?

DNA stores genetic instructions in the form of genes, allows for heritability through replication, and enables adaptation and evolution through mutations.

Define a gene.

A gene is a segment of DNA that contains the instructions for producing a specific protein or RNA molecule.

How does DNA replication contribute to heritability?

DNA replication allows cells to transmit genetic information to their offspring, preserving biological instructions across generations.

What role do mutations in DNA play in evolution?

Mutations can introduce new traits, enabling organisms to adapt to environmental changes, driving the diversity and evolution of life.

What is cytoplasm?

Cytoplasm is the jelly-like substance inside a cell, excluding the nucleus, where various cellular activities occur.

What are the two main components of cytoplasm?

Cytoplasm can be split into cytosol (the fluid portion) and organelles (structures like mitochondria and the Golgi apparatus).

Why is cytoplasm essential for cells?

Cytoplasm provides a medium for chemical reactions, facilitates molecular transport, and helps maintain the cell's shape.

What is the plasma membrane?

The plasma membrane is the thin, flexible boundary that surrounds a cell, composed of a phospholipid bilayer with embedded proteins.

What are the functions of the plasma membrane?

Selective permeability

Compartmentalization

Communication

Energy processes in some cells.

Why are lipids used in the plasma membrane?

Lipids are hydrophobic, making them excellent barriers to water-soluble substances, and their bilayer structure allows for membrane fluidity.

What would happen to a cell if its plasma membrane lost its selective permeability?

The cell would be unable to regulate what enters and exits, leading to potential toxicity and loss of homeostasis.

Why are DNA, cytoplasm, and plasma membranes considered universal features of cells?

They address fundamental challenges of life: inheritance, metabolism, and boundary maintenance.

What is the role of water in the cytoplasm?

Water acts as a solvent, provides thermal stability, and supports hydrogen bonding, making it ideal for chemical reactions.

How do proteins in the plasma membrane contribute to cell communication?

Proteins act as receptors, detecting signals from the environment and triggering responses within the cell.

What is the difference between DNA and RNA in terms of information storage?

DNA is used for long-term information storage, while RNA is not.

Give an example of how a mutation can lead to adaptation.

A mutation in bacteria that allows some individuals to digest a new sugar gives them a survival advantage in that environment.

What is the significance of the plasma membrane in energy production?

In some cells, like bacteria, the plasma membrane plays a role in generating ATP through processes like cellular respiration.

How does the cytoplasm support molecular transport?

The cytoplasm provides a connected environment where nutrients, waste products, and signaling molecules can move throughout the cell.

What is the relationship between the cytoplasm and cellular metabolism?

Cytoplasm offers a dynamic environment for all the chemical reactions that sustain life.

Why is the plasma membrane described as fluid?

The plasma membrane is fluid because lipids and proteins are constantly moving within the bilayer.