CB LECTURE 1 — Introduction to Cell Biology

What are cells?

The fundamental units of life

What does the cell theory state?

All living things are made of cells.

Why do we need to understand biology at the cellular level?

Because all living organisms are made of cells, and understanding how cells function helps us understand how organisms develop and function.

What are some major things a cell must be able to do?

1. To live or die

2. If die, often need to die in a controlled manner (apoptosis)

3. If live, then need energy-- how to store the energy (location and form?)

4. Communicate

5. Proliferate (or not)

6. Move (or not)

What is apoptosis?

A tightly regulated form of cell death.

Why does cell death need to be controlled?

Uncontrolled cell death could affect surrounding cells and the health of the entire organism.

Why is communication important to a cell?

Cells need information from their environment and other cells to determine whether conditions are appropriate for activities such as division and movement.

Why shouldn't a starved cell divide?

Cell division is energetically expensive, so dividing when nutrients are insufficient is unfavorable.

What are some major questions studied in cell biology?

What cells are made of

Why are model organisms useful in cell biology?

Many basic cellular processes are highly conserved among organisms, allowing researchers to learn about human cells by studying other organisms.

Give examples of highly conserved cellular processes.

Transcription and translation.

Which cytoskeletal proteins are highly conserved?

Actin and tubulin.

How did eukaryotic cells acquire mitochondria?

Through a symbiotic relationship with aerobic bacteria.

How did some eukaryotes later acquire chloroplasts?

A subset of single-celled eukaryotes acquired chloroplasts later in evolution. through endosymbiosis, a process where an early eukaryotic cell engulfed a photosynthetic bacterium, which then stayed inside and turned into an organelle.

Approximately when were mitochondria acquired?

About 1.5 billion years ago.

Why can studying other organisms teach us about humans?

Fundamental cellular mechanisms are conserved across many organisms.

What have model organisms taught us about cell-cycle control?

The guiding principles of cell-cycle control are shared among most eukaryotic cells.

Why is the malaria parasite an example of cellular complexity?

Even a unicellular organism has a complicated life cycle and must make many critical decisions.

What happens when a malaria parasite enters the human body?

It travels through the bloodstream to the liver, infects liver cells, undergoes nuclear divisions, and produces new parasites that infect red blood cells.

Why can malaria parasites hide from the immune system?

They can reside inside red blood cells.

What happens to an infected red blood cell when the parasite matures?

It bursts, releasing more parasites into the bloodstream.

What is leukocyte rolling?

The process in which a leukocyte rolls along the blood vessel wall before strongly adhering and leaving the bloodstream.

What happens when leukocyte surface proteins contact endothelial cells?

When leukocyte surface proteins contact endothelial cells during an immune response, they trigger a multi-step process called extravasation. This sequence allows white blood cells to slow down, firmly stick to blood vessel walls, and squeeze through the tissue to reach sites of infection or injury

What happens to signaling proteins associated with the leukocyte plasma membrane?

They undergo conformational changes. change their shape, or conformation, when activated by binding molecules. This shape shift triggers chemical signals inside the cell. It helps the white blood cell react to germs or swelling. [1, 2, 3, 4, 5]

What cytoskeletal processes should you recognize in The Inner Life of the Cell?

Actin polymerization and severing

What happens to ribosome subunits?

During protein synthesis, the small and large ribosome subunits join together on a messenger RNA (mRNA) strand to read the genetic code. When translation finishes at a stop codon, the subunits separate, release the new protein, and float freely in the cell to be reused for new protein synthesis. [1, 2, 3]

What happens to proteins entering the ER?

Proteins entering the ER pass through a channel called a translocon, where they fold into their correct shape and may be modified. They are then packaged into vesicles and transported to the Golgi apparatus.

What happens to vesicles from the ER?

They bud from the ER and are transported along microtubules by kinesin motors to the gologi apparatus They deliver newly made proteins and lipids for further sorting, modification, and packaging. [1, 2, 3, 4, 5]

What is the role of the Golgi in The Inner Life of the Cell?

It participates in processing and trafficking cellular materials.

What is exocytosis?

The secretion of soluble proteins into the extracellular space and delivery of transmembrane proteins to the plasma membrane.

How does the leukocyte ultimately leave the bloodstream?

It flattens, strongly adheres to endothelial cells, and migrates through the blood vessel wall