Cell structure and microscopy

Question 1

What are cells?

Answer 1

The basic unit of all living organisms. They contain genetic information in a nucleus or nuclei, a cytoplasm and ribosomes

Question 2

What is a tissue?

Answer 2

A group of similar cells which work together to perform a specific function

Question 3

What is an organ?

Answer 3

A group of tissues which work together to perform a specific function

Question 4

What is an organ system?

Answer 4

A group of organs that work together to perform a particular function

Question 5

State 8 organelles found in animal cells

Answer 5

Nucleus, mitochondria, ribosomes, rough endoplasmic reticulum, smooth endoplasmic reticulum, centrioles, golgi body, lysosomes

Question 6

What is the function of the nucleus?

Answer 6

To store and transmit genetic material

Question 7

What is the function of nuclear pores?

Answer 7

To allow substances to enter and exit the nucleus

Question 8

What is chromatin?

Answer 8

DNA wrapped around histone proteins

Question 9

Describe the structure and function of the rough endoplasmic reticulum

Answer 9

Studded with ribosomes, made up of membranes folded into cisternas. It synthesizes proteins destined to be secreted

Question 10

Describe the structure and function of mitochondria

Answer 10

Double membrane folded into chrisae. There’s fluid with matrix inside. It contains its own DNA (mDNA). It’s a site of ATP production through aerobic respiration

Question 11

What is the function of lysosomes? What do they contain?

Answer 11

They break down substances so they can be used. They contain hydrolytic enzymes that break down waste

Question 12

What is the function of vesicles?

Answer 12

To transport substances within cells

Question 13

What is the structure and function of ribosomes?

Answer 13

Two units made of protein and rRNA. They synthesize proteins

Question 14

Describe the structure of the Golgi body

Answer 14

It’s a membrane-bound organelle folded into cisternae

Question 15

What is the function of the Golgi body?

Answer 15

It modifies and processes lipids and proteins and packages them into vesicles.

Question 16

Describe the structure and function of lysosomes

Answer 16

Membrane-bound vesicles that contain hydrolytic enzymes that break down waste and toxins.

Question 17

Describe the structure of centrioles

Answer 17

A cylindrical bunch of protein called tubules. They’re often found in pairs which make up a structure called centrosome.

Question 18

Name the components of a chloroplast (7)

Answer 18

Inner membrane, outer membrane, grana, stroma, ribosome, thylakoid, intergranal lamellae

Question 19

What is an intracellular enzyme?

Answer 19

An enzyme that acts within cells. Ex catalase

Question 20

What is an extracellular enzyme?

Answer 20

An enzyme that is secreted by cells and functions outside of cells. Ex amylase

Question 21

Describe the steps involved in the production of an extracellular enzyme

Answer 21

1. DNA transcribed to produce mRNA in the nucleus
2. mRNA exits the nucleus and travels to a ribosome on the rER
3. Enzyme synthesized by the ribosomes in translation
4. Enzyme is packaged into a vesicle and sent to the Golgi apparatus where it’s repackaged and modified
5. The enzyme leaves the Golgi apparatus enclosed in a vesicle and undergoes exocytosis to exit the cell

Question 22

What is the function of the flagellum?

Answer 22

To move the cell

Question 23

What is the function of the pili?

Answer 23

They allow the bacteria to adhere to other cells or surfaces

Question 24

What is the function of plasmid DNA?

Answer 24

To provide beneficial genes which aid in the survival of the prokaryote.

Question 25

What is the function of the bacterial capsule?

Answer 25

It protects the cell from dry environments and it acts as a virulence factor which helps resist phagocytosis

Question 26

What is the magnification of a microscope the measurement of?

Answer 26

How many times bigger the image appears compared to the original object

Question 27

What is the formula for calculating magnification?

Answer 27

image size = actual size x magnification actual size = image size / magnification magnification = image size / actual size

Question 28

What is the purpose of staining specimens?

Answer 28

To visually distinguish different parts of a specimen and to increase contrast. Lots of cellular components are transparent

Question 29

What is differential staining?

Answer 29

A form of staining used to distinguish between different parts of the specimen using different stains

Question 30

How do light microscopes work?

Answer 30

They use lenses to magnify visible light passed through a specimen

Question 31

What is resolution?

Answer 31

A measurement of the clarity of an optical instrument. The minimum distance which two separate points can be distinguished by an optical instrument

Question 32

Describe how a Transition Electron Microscope works

Answer 32

High energy beam of electrons passed through a thin slice of specimen. More dense structures absorb more electrons so they appear darker. The image is focussed onto a fluorescent screen or photographic plate using magnetic lenses

Question 33

Describe how a Scanning Electron Microscope works

Answer 33

Beam of electrons focused on the surface of a specimen using electromagnetic lenses. Reflected electrons hit a collecting device and are amplified to produce an image on a photographic plate

Question 34

Why do electron microscopes have a higher resolution than light microscopes?

Answer 34

Electrons have a much shorter wavelength than light and so can distinguish much smaller structures

Question 35

What type of microscope typically produces naturally colored images?

Answer 35

Light microscope

Question 36

What type of electron microscope produces 2D images?

Answer 36

Transmission electron microscope because the electrons are passed through the specimen

Question 37

Give 5 advantages of light microscopes

Answer 37

-cheap -easy to use -can visualize living cells -portable and don't always require electricity -can visualize whole specimens

Question 38

Give 2 advantages of electron microscopes compared to light microscopes

Answer 38

They have much higher resolution and depth of field. They have much higher magnification.