Chapter 2: Basic components of living systems

Question 1

What are the different types of microscopes?

Answer 1

• Light microscopes
  *Transmission electron microscopes
  *Scanning electron microscopes
  *Laser scanning confocal microscopes

Question 2

features of light microscope?

Answer 2

• Poor resolution due to long wavelength of light
  *Living samples can be examined
• Colour image can be obtained

Question 3

features of TEM?

Answer 3

• high magnification and resolution
  *electrons pass through specimen to create image

Question 4

features of SEM?

Answer 4

*high magnification and resolution
*electrons bounce off the surface of specimen to create image

Question 5

features of LSCM?

Answer 5

• high resolution
  *3D imaging
  *laser light is used to create image

Question 6

what is the difference between resolution and magnification?

Answer 6

Resolution - the minimum distance between two objects in which they can still be viewed as separate.
Magnification - How many times larger the image is compared to the specimen

Question 7

Formula for magnification?

Answer 7

magnification = image/ actual

Question 8

types of sample preparations

Answer 8

• Dry mount
  *Wet mount
  *Squash slides
  *Smear slides

Question 9

Dry mount prep

Answer 9

Thin slices or whole specimens are viewed with just cover slip placed on top

Question 10

wet mount

Answer 10

specimen added to water before lowering coverslip with a mounted needle to prevent air bubbles

Question 11

squash slide

Answer 11

wet mounts which you push down on coverslip after to squash specimen to ensure a thin layer for light to pass is produced

Question 12

smear slides

Answer 12

created using edge of another slide to smear sample to create thin, smooth, even coated specimen, coverslip placed on top after smear

Question 13

staining

Answer 13

used to make certain cells and components more visible under a microscope

Question 14

electron microscope

Answer 14

*a beam of electrons has a very short wavelength which means there will be a high resolution
*image is created using electromagnet
*EM must be in vacuum as electrons are absorbed by air therefore non living organisms can be visualised

Question 15

cell theory

Answer 15

*both plant and animal tissue is composed of cells
*cells are the basic unit of all life
*cells only develop from existing cells

Question 16

cell theory: 1665

Answer 16

cells first observed by Robert Hooke using thinly sliced cork

Question 17

cell theory: 1674-83

Answer 17

first living cells observed

Question 18

cell theory: 1832

Answer 18

evidence for the origin of new plant cells

Question 19

cell theory:1833

Answer 19

nucleus first observed

Question 20

cell theory: 1837-38

Answer 20

Birth of universal cell theory

Question 21

cell theory: 1844

Answer 21

evidence for origin of animal cells

Question 22

cell theory: 1860

Answer 22

spontaneous generation disproved

Question 23

nucleus

Answer 23

the area where dna synthesis occurs, where lots of genetic material is found and is what controls the cell
* contains nucleolus
*contains chromatin
*contains nuclear envelope
*contains nuclear pores

Question 24

nucleolus

Answer 24

an area within the nucleus and is responsible for producing ribosomes
* is composed of protein and rna
* used to produce ribosomes

Question 25

chromatin

Answer 25

Uncondensed dna *coils and condenses to form chromosomes

Question 26

Nuclear envelope

Answer 26

two lipid bilayer membranes

Question 27

nuclear pores

Answer 27

allows mRNA to leave nucleus

Question 28

mitochondria/on

Answer 28

The site of aerobic respiration *is the site of the final stages of cellular respiration, organic molecules are made available for the cell to use by the production of the molecule ATP *a cell with more mitochondria is more active *they have double membrane, inner is highly folded to form structures called cristae and the fluid is called the matrix *contains small amounts of dna

Question 29

lysosomes

Answer 29

*specialised forms of vesicles and contains hydrolytic enzymes *Responsible for breaking down waste material in cells *digest and breaks down bacteria and other pathogens and organelles *involved in programmed cell death/apoptosis

Question 30

vesicles

Answer 30

membranous sacs and have a storage and transport role

Question 31

ribosomes

Answer 31

*small *made up of 2 sub units of protein and rna * 80s - larger ribosomes found in eukaryotic cells 70s - smaller ribosomes found in prokaryotic cells, mitochondria and chloroplasts *are the site of protein synthesis

Question 32

golgi apparatus

Answer 32

*compact structure formed of cisternae and doesn't contain ribosomes *modifies proteins and 'packages' them into vesicles (may be secretory vesicles if proteins intend to leave cell) or (lysosomes which stay in cell) * protein enters as primary structure and leaves as a formed protein *golgi vesicle - transport

Question 33

centrioles

Answer 33

a component of the cytoskeleton present in most eukaryotic cells * two centrioles form a centrosome

Question 34

endoplasmic reticulum (ER)

Answer 34

a network of membranes enclosing flattened sacs called cisternae

Question 35

rough endoplasmic reticulum (RER)

Answer 35

has ribosomes bound to surface and is responsible for the synthesis and transport of proteins *secretory cells have more RER than cells that do not release protein

Question 36

smooth endoplasmic reticulum (SER)

Answer 36

responsible for lipid and carbohydrate synthesis and storage

Question 37

Flagella

Answer 37

used primarily to enable cells mobility *used in some cells as a sensory organelle, detecting chemical changes in the cells environment

Question 38

cilia

Answer 38

*can be mobile or stationary *stationary cilia - present on thhe surface of many cells and is important in sensory organs such as nose *mobile cilia, beat in rhythmic manner, creating a current and causing fluids or objects adjacent the cell to move *mobile cilia is present in trachea to waft mucus away from the lungs

Question 39

cytoskeleton

Answer 39

a network of fibres necessary for the shape and stability of a cell *microfilaments - formed from the protein, actin. Is responsible for cell movement and contraction *microtubules - globular tubulin in proteins polymerise to form tubes that determine the shape of a cell Spindle fibres are also formed of microtubules *Intermediate fibres - give mechanical strength to cells and help maintain integrity

Question 40

vacuole

Answer 40

*filled with fluid surrounded by a single membrane called a tonoplast *vacuole makes cell turgid and therefore provides support *temporary store for sugars and amino acids *the pigment may colour petals to attract pollinators

Question 41

chloroplast

Answer 41

*surrounded by a double membrane *contains thylakoids, folded membranes embedded with pigment. *multiple thylakoids together are called a granum or grana(plural) *fluid filled stroma which contains enzymes for photosynthesis *stroma is where light independent reactions occur *found in plant cells

Question 42

cell wall

Answer 42

*provides strength to cell *found in plant and fungi cells *in plants - are made of cellulose *in fungi - are made of chitin *are freely permeable *surrounds cell surface membrane

Question 43

What are the key differences between prokaryotic and eukaryotic cells?

Answer 43

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus, membrane-bound organelles, and are larger.

Question 44

What is the difference between light microscopes and electron microscopes?

Answer 44

Light microscopes use visible light to magnify objects, with a maximum resolution of 0.2 µm. Electron microscopes use electron beams and have a higher resolution, allowing for more detailed images

Question 45

What is the function of the nucleus in a cell?

Answer 45

The nucleus contains the cell’s genetic material (DNA) and is responsible for controlling the cell’s activities, including growth, metabolism, and reproduction.

Question 46

What is the function of the mitochondrion?

Answer 46

Mitochondria are the powerhouse of the cell, involved in energy production through aerobic respiration, generating ATP

Question 47

What is the ribosome’s function in the cell?

Answer 47

Ribosomes are responsible for protein synthesis, translating mRNA into polypeptide chains

Question 48

What is the function of the endoplasmic reticulum (ER)?

Answer 48

The rough ER synthesizes proteins that are secreted, incorporated into membranes, or sent to lysosomes. The smooth ER synthesizes lipids and detoxifies drugs and poisons

Question 49

What is the role of the Golgi apparatus?

Answer 49

The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Question 50

What does the lysosome do?

Answer 50

Lysosomes contain digestive enzymes that break down waste materials and cellular debris.

Question 51

What is the function of the centriole in animal cells?

Answer 51

Centrioles play a key role in cell division by organizing the spindle fibers during mitosis and meiosis.

Question 52

What is the structure of the plasma membrane?

Answer 52

The plasma membrane is composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrate chains, forming a fluid mosaic model.

Question 53

What is the function of the plasma membrane?

Answer 53

The plasma membrane controls the movement of substances into and out of the cell, provides structural support, and facilitates communication between cells.

Question 54

What are the key features of prokaryotic cells?

Answer 54

Prokaryotic cells are smaller, lack a nucleus, and have a single circular DNA molecule, 70s ribosomes, a cell wall (often made of peptidoglycan), and a plasma membrane. Some also have flagella

Question 55

What is the function of the plasmid in prokaryotic cells?

Answer 55

Plasmids are small, circular DNA molecules that carry extra genes, such as those for antibiotic resistance, and are independent of the chromosomal DNA.

Question 56

What are the three main components of the cytoskeleton?

Answer 56

The three components are microfilaments (actin filaments), intermediate filaments, and microtubules.