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

CAMs

Cell-adhesion molecules

Properties of stem cells

Can divide endlessly and differentiate along different pathways

Stem cell niche

Locations that have stem cells and provide an environment for stem cells to differentiate and/or regenerate

Type I vs. Type II. Pneumocyte

Type I - Increased SA:V Ratio, very thin and flat to increase diffusion

Type II - Decreased SA:V ratio, secretes surfactant to alveolar lumen

Promoter

A DNA sequence that initiates transcription of a gene by RNA polymerase.

Epigenesis

Development of patterns of differentiation in cells of multicellular organisms through processes such as DNA methylation and histone modification.

Histone Methylation

Adding a methyl group to the tail (methylation) maintains the positive charge of histone amino acid tails, making DNA more coiled and reducing transcription.

Phenotype

Combination of gene expression and environmental factors

Alternative splicing

Exons are selectively removed to form different versions of proteins from the same gene

tRNA-activating enzyme

The enzyme joins ATP to an amino acid

• Charged’ amino acid is linked to tRNA

Degeneracy

Refers to the genetic code's feature where multiple codons can code for the same amino acid

Phenotype plasticity

Refers to the ability of an organism to change its phenotype in response to environmental influences (genotype is not influenced)

Emergent properties

traits or characteristics that arise from the complex interactions of simpler components within a biological system, which cannot be predicted by understanding the individual parts alone.