IB Bio Keywords

All chapters

Penicillin

• Binds to bacterial transpeptidase

• Gets converted to a reactive form

• Permanently bonds to and inactivates the enzyme

• Prevents bacterial cell wall synthesis, causing lysis

Metabolism

Complex network of interacting and interdependent chemical reactions occuring in a living organism

Anabolic

Building of complex molecules from simple ones (via. condensation reactions)

Catabolic

Breakdown of complex molecules into simple ones (via hydrolysis reactions)

Conditions living organisms need to maintain for life

Metabolism, reproduction, sensitivity (responsiveness), homeostasis, excretion, nutrition and growth (movement)

Outline why viruses are not considered living organisms

• Viruses are not considered living because they cannot carry out all life functions independently

• Viruses lack metabolism and must rely on metabolic events in a host cell to generate its component parts

• A virus can therefore not reproduce autonomously and must infect a cell in order to replicate

Why are hydrothermal vents considered a possible site for the origin of life?

Hydrothermal vents provide a stable environment with the necessary chemical ingredients and energy sources, such as heat and minerals, that could support the formation of early life forms.

The cell theory states that

• All cells come from pre-existing cells

• All living organisms are composed of one or more cells

• The cells are the smallest unit of self-sustaining life

Structure of eukaryotic cell

• Double-membrane nucleus with pores (containing DNA bound to histones)

• Membrane-bound organelles, including mitochondria, endoplasmic reticulum, and Golgi apparatus

• Cytoskeleton of microtubules and microfilaments

• Vesicles or vacuoles

• 80s ribosomes

Atypical eukaryotic cells

• Red blood cells

• Aseptate fungal hyphae

• Skeletal muscle cells

• Phloem sieve tubes

Outline the lytic cycle in viruses

1. Attachment: Virus binds to the host cell.

2. Penetration: Virus injects its genetic material into the host cell.

3. Biosynthesis: Viral DNA replicates, and viral proteins are produced.

4. Maturation: New viral particles are assembled.

5. Lysis: The host cell bursts, releasing new viruses.

What happens to the viral DNA during the lysogenic cycle?

It is integrated into the host genome and replicated along with it.

Function of cholesterol

Stabilizes membranes at high temperatures and prevents stiffening at low temperatures