Cell Biology and Division

This set of flashcards covers the foundational concepts of cell biology, including cell structure, organelles, DNA replication, and the phases of mitosis and the cell cycle as described by Dr. Sarah List.

What are defined as the structural, functional, and biological units of life?

Cells

What are the three basic components found in a eukaryotic animal cell?

The plasma membrane, the cytoplasm, and the nucleus.

In terms of the cell's internal contents, what is the difference between the cytosol and the organelles?

The cytosol is the jelly-like water medium, while the organelles are the 'little organs' contained within it.

What is the structure of the cell membrane according to the transcript?

It is a lipid bilayer with an intracellular side and an extracellular side.

Why does the cell membrane spontaneously self-arrange into a double layer?

Because it contains phospholipids with hydrophobic (water-disliking) fatty tails that face each other and hydrophilic (water-loving) phosphate heads that face the exterior.

What model is used to describe the cell membrane as a mixture of phospholipids, proteins, and other structures?

The fluid mosaic model

What is the primary function of the nucleus?

It acts as the control center of the cell and stores genetic instructions in the form of DNA.

What structure within the nucleus is responsible for manufacturing the RNA for ribosomes?

The nucleolus

Under what specific condition does DNA tighten into organized bundles called chromosomes?

Only during cell division or cell copying.

What enzyme is responsible for untwisting and copying DNA strings?

DNA polymerases

According to the transcript, what are the four bases of DNA and their specific pairings?

Adenine, thiamine, guanine, and cytosine; adenine always pairs with thiamine and guanine always pairs with cytosine.

What are the two primary functions of DNA polymerase during replication?

It adds new bases to form pairs at one end and performs proofreading to check accuracy at the other end.

What approximate percentage of the cell membrane is composed of the lipid bilayer?

$$75\%$$

What are the two types of endoplasmic reticulum (ER) and how are they distinguished?

Rough ER, which has ribosomes on the outside, and smooth ER, which does not.

What are the specific functions of the smooth endoplasmic reticulum?

It synthesizes phospholipids and steroid hormones, and it can store calcium.

Which organelle is responsible for sorting, modifying, and repackaging products from the rough ER?

The Golgi apparatus

What is the function of a lysosome?

It acts as the digestive stomach of the cell, using enzymes to break down unneeded cellular bits, such as damaged organelles.

What is 'autophagy'?

A process of 'self eating' where the cell recycles its own waste contents using lysosomes.

What is the role of the mitochondria?

They are the powerhouse of the cell, responsible for making high quantities of $ATP$ (adenosine triphosphate).

What is the difference between the roles of microtubules and microfilaments like actin?

Microtubules maintain cell structure and control DNA movement during division, while microfilaments are important for muscle contraction and cell cleavage (splitting).

What is the key difference between mitosis and meiosis?

Mitosis is asexual division creating two identical daughter cells, while meiosis produces gametes (egg and sperm) with $50\%$ of the original genetic content.

What happens during the $G_1$ phase of the cell cycle?

The cell checks its organelles and synthesizes new ones to ensure it has enough for two functional cells.

What occurs during the $S$ (synthesis) phase of the cell cycle?

DNA replication

What is the correct order of the phases within mitosis?

Prophase, metaphase, anaphase, and telophase, followed by cytokinesis.

What event characterizes prophase?

Chromosomes condense to become visible, spindle fibers form, and the nuclear membrane breaks down.

What occurs during metaphase?

Chromosomes line up neatly across the center of the cell and attach to mitotic kinetochores.

What happens during anaphase?

The centromeres split and the individual chromatids (now called chromosomes) are pulled toward opposite poles.

What is the final process of the cell cycle that results in the cell splitting into two?

Cytokinesis