Cell Biology and Membrane Transport Flashcards

These flashcards cover cell structure, microscopy, cell division, transport mechanisms, and food tests based on the lecture material.

What is the basic unit of life from which larger structures like tissues and organs are made?

A cell

On average, how many cells are in a human body?

$37$ trillion

What is the function of the cell nucleus?

Controls the activities of the cell and contains genetic material

Which cell organelle is the site of protein synthesis?

Ribosome

What is the role of the cell membrane?

Controls what goes in and out of the cell and contains receptor molecules

What is the function of mitochondria?

Releases energy for the cell to utilise through the process of respiration

Which organelle is made of cellulose and prevents a plant cell from bursting or collapsing?

Cell wall

What role do chloroplasts play in plant cells?

They contain chlorophyll to absorb light energy for the process of photosynthesis

How is magnification defined?

The number of times larger an image is compared with the real size of the object

What is the definition of resolution in microscopy?

The ability to distinguish between $2$ points

What are the two types of electron microscopes and what kind of images do they produce?

Transmission Electron Microscope (TEM) produces $2D$ images, and Scanning Electron Microscope (SEM) produces $3D$ images

What is the maximum magnification of a light microscope?

$$\times 1500$$

Why can electron microscopes produce clear images at magnifications up to $2$ million times?

Because they have a much better resolution than light microscopes

What is cell differentiation?

The process by which an unspecialised cell changes into a specialised cell to carry out a particular role

Which organisms are classified as eukaryotes?

Plants, Animals, Fungi, and Protists

What characterizes a prokaryotic cell?

They do not have a nucleus; an example is bacteria

What are the extra small rings of DNA found in some bacteria called?

Plasmids

Where is DNA found in a prokaryotic cell?

Loose in the cytoplasm

How many total chromosomes do humans have?

$46$ total ($23$ pairs)

What are the three main stages of the cell cycle?

$1.$ Growth and DNA replication, $2.$ Mitosis, and $3.$ Cytokinesis

What happens to the chromosomes during mitosis?

They line up in the middle of the cell, and copies are pulled to opposite ends before the nucleus splits into $2$ identical nuclei

What is the result of cytokinesis?

The cytoplasm and cell divide to form $2$ genetically identical daughter cells

What is the difference between totipotent and multipotent stem cells?

Totipotent cells can differentiate into any type of cell (found in embryos), while multipotent cells can differentiate into a certain range of cell types (found in adults)

What is diffusion?

The net movement of molecules from an area of high concentration to an area of low concentration

What four factors affect the rate of diffusion?

$1.$ Temperature, $2.$ Concentration gradient, $3.$ Surface area, and $4.$ Diffusion distance

How does active transport differ from diffusion regarding energy and concentration?

Active transport requires energy and moves molecules from low to high concentration (against the gradient), while diffusion is passive and moves from high to low

What is the equation used to work out the surface area to volume ratio?

$$\text{SA:Vol} = \text{surface area (cm}^2\text{)} / \text{volume (cm}^3\text{)}$$

By what process do oxygen and carbon dioxide move between the alveoli and the bloodstream?

Diffusion

How is the small intestine adapted for efficient nutrient absorption?

It has Villi which provide a huge surface area, a good blood supply, and walls that are only one cell thick

What is osmosis?

The diffusion of water molecules from a high water concentration to a low water concentration across a partially permeable membrane

In plant cells, what does 'turgid' mean?

The cell is swollen and firm because it has taken in water by osmosis, pushing the cytoplasm against the cell wall

What happens to an animal cell if it is placed in distilled water?

It bursts (lysis) because water enters by osmosis and there is no cell wall

What is the food test for starch?

Using iodine solution; the orange-brown solution turns blue-black if starch is present

How do you test for proteins and what is the positive result?

Use Biuret reagent; the blue solution turns lilac if protein is present

What is the positive result for the Benedict's reagent test for sugars?

The solution changes from blue to green, orange, or brick-red depending on the concentration