overview/essentials

Question 1

what is a prokaryotic cell?

Answer 1

a prokaryotic cell is a cell that doesn’t have any membrane bound organelle or a nucleus.
most of the genetic information forms in loops called plasmids.

Question 2

what are some of the structures found in prokaryotic cells?

Answer 2

the four main structures are the cell membrane, cytoplasm, ribosomes and genetic material.
some of the other structures are plasmids, the cell wall & capsules, pili like structures, and flagella.

Question 3

what are the two groups of prokaryotes?

Answer 3

bacteria & archaea

Question 4

what are eukaryotic cells?

Answer 4

eukaryotic cells are more complex than prokaryotic cells. they have membrane bound organelles, including the nucleus which contains genetic material.
each organelle has a specific function within the cell, and together they carry out biochemical processes and reactions, including respiration and photosynthesis.
they can be unicellular or multicellular.

Question 5

what are some unicellular eukaryotes?

Answer 5

paramecium, amoeba, and euglena.

Question 6

what are the different types of microscopes?

Answer 6

light, fluorescence, TEM, SEM

Question 7

how do light microscopes work?

Answer 7

a light source is passed through a condensor and then a thin specimen.
the beam passes through the convex objective lense where the image is magnified.
can magnify up to 1500x.
both living and non-living specimens can be viewed.

Question 8

how do flurorescence microscopes work?

Answer 8

it is used to view images of specific parts that have been limited by the reolving power of the light microscope.
the sample is labelled with a fluroescent substance which attaches to the structure to be viewed.
it’s then illuminated by a high intensity light source to emit light.

Question 9

how do transmission electron microscopes work (TEM)?

Answer 9

TEM uses a beam of electrons that is transmitted through a thin specimen, as the beam passes through the specimen it interacts with the atoms in the specimen, some electrons are scattered and some pass through.
the electrons that pass through are focused using electromagnetic lenses onto a detector or screen to form an image.
the image contrast is formed based on how the electrons interact with the material, where dense areas scatter more electrons, appearing darker, while less dense areas appear lighter.
it produces 2D images with very high resolution (up to atomic level). up to 10 million x magnification.

Question 10

how do scanning electron microscopes work (SEM)?

Answer 10

SEM uses a focused beam of electrons that scans the surface of the specimen. when the electron beam hits the surface, it interacts with the atoms of the sample, causing the emission of secondary or backscattered electrons from the surface.
the emitted electrons are collected by detectors to form an image, these detectors capture the electrons scattered from the surface, creating a detailed 3D image of the surface topography.
Contrast in SEM images is based on surface structure and the composition of the material, as different elements reflect and emit electrons differently.
it typically achieves magnification ranging from 20x to 30000x.
the samples need to be coated with a thin layer of conductive materoal (gold or carbon).

Question 11

what organelles can be seen under a school light microscope?

10-40x

Answer 11

the organelles that can be seen are the nucleus & nuclear membrane, cytoplasm, cell membrane, chloroplasts, vacuole (tonoplast & cell sap) and cell wall.

Question 12

what organelles can be seen with a fluorescence microscope?

Answer 12

the organelles visible are the nucleus, mitochondria, endoplasmic reticulum (ER), golgi apparatus, cytoskeleton and, lysosomes.

Question 13

what organelles can be seen with an SEM?

Answer 13

the visible organelles are the cell membrane, surface features, and cytoskeleton, since it only has images of the cells surface, but does not show internal structures.

Question 14

what organelles are visible with a TEM?

Answer 14

the visible organelles are the nucleus, mitochondria, endoplasmic reticulum, ribosomes, golgi apparatus, lysosomes and peroxisomes, chloroplasts, cytoskeleton, cell membrane.

Question 15

what organelles can be seen with an adv light microscope?

800-2000x

Answer 15

the visible organelles are the cell wall, nucleus & nuclear membrane,chloroplasts, vacuole, cytoplasm, cell membrane, golgi body, mitochondria, nucleolus

Question 16

what is the nucleus?

Answer 16

the nucleus is the ‘control centre’ of the cell and contains the cell’s genetic material (DNA) and coordintes growth, metabolism, protein synthesis, and cell division.
it is surrounded by a double nuclear membrane, which has pores to regulate the entry and exit of materials.

Question 17

what is the nucleolus?

Answer 17

the nucleolus is found in the nucleus and is responsible for the production of ribosomes.

it is made up of granular and fibril components in a matrix, and contains DNA, RNA and proteins.

Question 18

what is the mitochondria?

Answer 18

The mitochondria is the site of aerobic cellular respiration, the chemical reactions that preoduce energy in the form of a molecule called ATP (adenosine triphosphate).

mitochondria have a double membrane, the inner membrane is folded into structures called cristae, which increase surface area for energy production. they also contain their own DNA.

Question 19

what is the endoplasmic reticulum (ER)?

Answer 19

the endoplasmic reticulum serves many roles in the cell, including calcium storage, protein synthesis, and lipid metabolism.

the rough ER is studded with ribosomes, and synthesizes proteins destined for membranes, secretion or organelles.
the smooth ER lacks ribosomes and is involved in lipid synthesis, detoxification, and calcium ion storage.
it is a network of membranous tubules and sacs (cisternae), and extends from the nuclear envelope throughout the cytoplasm.

Question 20

what is the golgi apparatus (golgi body)?

Answer 20

the golgi body is made up of stacks of flattened membrane-bound sacs (cisternae) and is located near the ER and nucleus.
it modifies, sorts and packages proteins and lipids for secretion or delivery to other organelles.

Question 21

what are ribosomes?

Answer 21

ribosomes are very small, spherical organelles that are composed of RNA and proteins. they can be found floating freely in the cytoplasm or attached to the rough ER.
they are the sites of protein synthesis, where mRNA is translated into polypeptides (proteins) by linking amino acids together.

Question 22

what are lysosomes?

Answer 22

lysosomes are membrane-bound vesicles filled with hydrolytic enzymes, found dispersed throughout the cytoplasm.
they act as the waste disposal system by breaking down and dissolving unwanted or damaged cellular materials. they contain enzymes that digest the cellular debris, pathogens, and organelles through autophagy.

Question 23

what are perioxisomes?

Answer 23

they are small membrane-bound organelles found found in the cytoplasm and contain enzymes like catalase.
they break down fatty acids and detoxify harmful substances, such as hydrogen peroxide.

Question 24

what is the cytoskeleton?

Answer 24

the cytoskeleton provides structural support, maintains the shape of the cell, and aids in movement (of the cell and within the cell). it also helps with cell division.
it’s composed of three types of protein filaments (microfilaments, intermediate filaments, microtubules) and is found distributed throughout the cytoplasm.

Question 25

what is the cytoplasm?

Answer 25

it is made up of water, salts, and organic molecules, and occupies the space between the plasma membrane and the nucleus.
it is a gel-like fluid that fills the cell and suspended the organelles, and is the site of many metabolic reactions.

Question 26

what are vacuoles?

Answer 26

vacuoles are large membrane-bound sacs filled with fluid, and are central in plant cells, smaller and more numerous in animal cells.
they store nutrients, waste products and water.
in plant cells, the central vacuole helps maintain turgor pressure, supporting the cell’s structure.

Question 27

what are chloroplasts?

Answer 27

chloroplasts are found in the cytoplasm of plant cells, and contain the green pigment chlorophyll and have a double membrane. inside they have have membrane-bound sacs called thykaloids stacked into grana, surrounded by stroma.
they conduct photosynthesis by conerting light energy into chemical energy (sugar).

Question 28

what are centrosomes?

Answer 28

centrosomes are made up of two centrioles, each composed of microtubules arranged in a specific pattern. they are located near the nucleus in animal cells.
they organise microtbules and play a key role in cell division. they help in forming the spindle fibres used to seperate chromosomes during mitosis.

Question 29

what is the cell wall?

Answer 29

the cell wall is a rigid, outer layer found in plant cells, that provides structural support, protection, and helps maintain the cell’s shape. it is primarily made up of cellulose.

Question 30

what is the cell membrane?

Answer 30

the cell (or plasma) membrane is made up of a phospholipid bilayer, embedded with proteins, carbohydrates and cholesterol.
it is a selective barrier that regulates the passage of substances in and out of the cell, and maintains the internal environment of the cell.

Question 31

how do you estimate the size of cells using a scale bar?

Answer 31

1. use scale bar to calculate magnification.
   magnification=image size (measured with ruler)/real size (number on the scale bar)
2. substitute values into the equation for actual size.
   actual size=image size/magnification
   __________________________________________________

divide the number of cells that cross the diameter of the field of view into the diameter of the field of view.
e.g. if the diameter of the field is 5mm, and you estimated 50 cells laid out end to end would cross the diameter, then
5mm/50 =0.1mm/cell.

Question 32

what is the cell theory?

Answer 32

• cells are smallest unit of life
• all living things are made up of cells
• all cells come from pre-existing cells.

Question 33

what is a phospholipid bilayer?

Answer 33

a phospholipid is a lipid that contains phosphate groups, so a bilayer is two of them.
the lipid tail is hydrophobic and the phosphate head is hydrophilic.
in the phospholipid bilayer the hydrophobic tails face each other and the hydrophlic heads face into the cytoplasm and the environment.

Question 34

what is the fluid mosaic model?

Answer 34

cell membranes are like a mosaic of different protein molecules mixed with phospholipids.
carbohyrdate molecules are attached to the proteins and lipids on the side facing the external environment.
the complex molecules are called glycoproteins and glycolipids.
the phospholipids and proteins can move, giving cell membranes fluidity and flexibility.

Question 35

what are the word and chemical equations for photosynthesis?

Answer 35

carbon dioxide + water + light energy -> glucose + oxygen

6CO(2) + 6H(2)O +light energy -(chloroplast)-> C(6)H(12)O(6) + 6O(2)

() mean subscript

Question 36

what is passive transport?

Answer 36

passive transport is the movement of molecules across a semi-permeable membrane without the use of energy (ATP).
this occurs along the concentration gradient, meaning the molecules move from an area of high concentration to one of low concentration until equilibrium is reached.
there are two different types; diffusion and osmosis (and facilitated diffusion).

Question 37

what is active transport?

Answer 37

active transport is the movement of molecules across the cell membrane against their concentration gradient (low to high), which requires energy in the form of ATP.

Question 38

what is diffusion?

Answer 38

diffusion is the movement of molecules from high to low concentration.
it is dye to random movement of particles.
it eventually results in an equilibrium.
lipid soluble moelcules and very small molecules like oxygen and carbon dioxide can pass directly through the lipid bilayer.

Question 39

what is facilitated diffusion?

Answer 39

facilitated diffusion is the movement of larger or polar molecules (e.g. glucose, ions) through the membrane via transport proteins or channels.

Question 40

what is osmosis?

Answer 40

osmosis is the movement of water across a semi-permeable membrane from an area of high concentration to one of low concentration.
it works the same as diffusion.

Question 41

what are the different types of solutions?

Answer 41

hypertonic, isotonic, hypotonic

Question 42

what is a hypertonic solution?

Answer 42

a hypertonic solution is one with a greater solute conentration outisde of the cell than inside.
water moves out of the cell and the cell shrinks.

Question 43

what is an isotonic solution?

Answer 43

an isotonic solution is one with the same concentration as the inside of the cell.
it is the “ideal” conditons.

Question 43

what is a hypotonic solution?

Answer 43

a hypotonic solution is one with a smaller solute concentration than inside the cell.
water moves into the cell and causes the cell to expand.
they expand and can burst.

Question 44

what is endocytosis and exocytosis?

Answer 44

exocytosis and endocytosis occyr when a particle is too big to move through the cell membrane by diffusion or active transport.

Question 45

what is endocytosis?

Answer 45

endocytosis is when a large particle needs to be moved into a cell and the cell membrane changes its shape to surround the particle, engulfing it.
if a solid particle is engulfed its called phagocytosis and if a fluid is engulfed it’s pinocytosis.

Question 46

what is exocytosis?

Answer 46

exocytosis is the