A2.2 cell structure

Question 1

magnification
resolution

Answer 1

how many times a specimen has been enlarged
how clean specimen is shown

Question 2

what is magnification

Answer 2

increase of an objects image size compares to its actual size
equation= magnification= measures image size/ actual specimen size

Question 3

light microscope

Answer 3

visible light passing through living or dead specimens
can be stained or tagged

Question 4

electron microscope

Answer 4

use electrons passing through a specimen to form an image

Question 5

differences between light and electron microscope

Answer 5

LIGHT ELECTRON
cheap expensive
easy specimen preparation complex specimen preparation
lower resolution and enlargement much higher resolution and enlargement
specimens may be living or dead specimens are dead in fixed material
can be stained, tagged has two types; SEM, TEM

Question 6

how electron microscopes work

Answer 6

electrons have a shorter wavelength than light
-electrons absorbed by denser parts of sample
and when picked up by electron detector, forms an image
-only dead specimens and only produced in black and white

Question 7

SEM and TEM microscopes

Answer 7

SEM (scanning( TEM (transmission)
-beam of electrons beams of electrons through thin sections
scanning surface of specimen view of inner structure
-3D -2D
-higher resolution

Question 8

techniques used in electron microscopy

Answer 8

1) Freeze fracture microscopy
= freezing sample, using specialized tool to break sample into smaller pieces, which are observed under microscope to see internal structure. It it used to visualize structures like internal plasma membranes

2)cryogenic electron microscopy
= freezing specimen in ice, to stabilize molecules and uses computer enhancement

Question 9

techniques used in light microscopy

Answer 9

1) immunofluorescence
=involves antibodies that have dyes already combined with them and these specific antibodies combine with specific antigens on a structure being used. When antibody bring antigen, structure is ‘tagged,’ with immunofluorescence, and will emit light when irradiated, making bright colours

2) fluorescent dyes/stains
=dyes that combine with specific cellular components, when irradiated the parts that accept the dye will fluoresce. colors produce more visibility

Question 10

structures common to all cells

Answer 10

1) DNA as genetic material
-has ability to form large molecules from small building blocks, nucleotides
-controls production of enzymes (controlling chemical reactions)

2) cytoplasm continued mostly of water
-consists cytosols, mostly water with carbon compounds + ions, needed for day to day activities

3) a plasma membrane, composed of lipids surrounding cytoplasm
-membrane used for protection
-major component is a bilayer
-engages in communication and transport between cells

Question 11

prokaryotic cells

Answer 11

-smaller and simpler than eukaryotic cells
-less than one micrometer
-mostly unicellular
-include bacteria and archea

Question 12

list of features of a prokaryotic cell

Answer 12

-cell wall
-plasma membrane
-flagella
-pili
-ribosomes
-the nucleiod

Question 13

cell wall and plasma membrane in prokaryotic cells

Answer 13

cell wall:
structure= carb-protein complex (peptidoglycan), layer is called capsule
function=
-protects and maintains shape
-keeps cell from rupturing when water pressure is greater in cell

plasma membrane:
-found just inside cell wall
-controls movement of materials in and out of cell, and plays a role in binary fission

Question 14

gram positive and gram negative

Answer 14

• a way to classify bacteria is their ability to retail a crystal violet dye
  gram positive= bacteria that have cell walls that have a violet appearance when exposed to crystal violet. E.G: bacillus and staphylococcus

gram negative= bacteria do not retain this dye and do not appeal violet

Question 15

Pilli and flagella in prokaryotic cells

Answer 15

Pilli=
-hair-like growths on the outside of the cell wall.
-used for attachment and joining bacterial cells in preparation for sexual reproductions

Flagella=
-longer than pilli
-allow cell to move and are anchored to cell wall and plasma membrane

Question 16

cytoplasm in in prokaryotic cells

Answer 16

-occupies complete interior of cell
-all cellular processes take place in the cytoplasm in prokaryotes

Question 17

ribosomes in prokaryotic cells

Answer 17

-composed of a protein and an rRNA
-small structures and occur in large numbers
-site of protein synthesis

Question 18

the nucleoid region in prokaryotic cells

Answer 18

-non compartmentalized and contains long, continuous thread of DNA.
-not surrounded by membrane
-involved in cell control and reproduction

Question 19

plasmids in prokaryotic cells

Answer 19

bacteria may also contain plasmids
-small, circular DNA molecules not connected to main bacterial chromosome
-replicate independently
-can help bacteria adapt to unusual circumstances

Question 20

what is binary fission and steps

Answer 20

simple way that prokaryotic cells divide. During this process, DNA is copied resulting in two daughters chromosomes, that attach to different regions of the plasma membranes. The cell elongates using specialized fibers and divides to form two genetically identical daughter cells.

Question 21

features of eukaryotic cells

Answer 21

-organelles enable compartmentalization, enabling different chemical reactions to take place
-contains a nucleus

nucleus structure:
-a nucleus with chromosomes made of DNA bound to histones, contained in a double membrane with pores

membrane bound cytoplasmic organelles:
-mitochondria
-endoplasmic reticulum
-golgi apparatus

variety of vesicles or vacuoles:
-lysosomes
-cytoskeleton of microtubes
-microfilaments

Question 22

organelles in eukaryotic cells

Answer 22

-endoplasmic reticulum
-ribosomes
-Golgi apparatus
-mitochondria
-nucleus
-vacuoles
ONLY IN ANIMALS: -lysosomes, centrosomes, cilia, flagella
ONLY IN PLANTS: -chloroplast, cell wall, central vacuole

Question 23

cytoplasm

Answer 23

-region all organelles are found
-made from cytosol
-in eukaryotes it includes small fibers and rods called cytoskeleton that creates a complex internal structure

Question 24

cytoskeleton

Answer 24

are fibers made of proteins that provide functions like:
1) maintaining cell shape
2) anchors some organelles
3)helps cellular movement

it contains three types:
1) acting filament- functions in cell division and cell movement
2) intermediate filament- reinforces cell shape and anchors some organelles
3) microtubules- shape and supporting cell

Question 25

endoplasmic reticulum

Answer 25

-extensive channel of networks extending all over cell
-participants in protein and lipid synthesis
-transports minerals
SMOOTH ER:
-has enzymes embedded on its surface
-produces sex hormones
-detoxification of drugs in the liver
-storage of calcium ions in muscle cells
-helps liver release glucose into bloodstream

ROUGH ER
-engages in proteins development and transportation
-there proteins may become parts of membrane, enzymes or messengers
-closer to nucleus

Question 26

ribosomes

Answer 26

-dont have exterior membrane
-conduct protein synthesis in a cell
-can be found free or attached to ER
-composed of a type of RNA + protein
-larger and denser than in prokaryotic
-80S in eukaryotic

Question 27

golgi apparatus

Answer 27

flattened sacs called cisternae, stacked on one another
e.g-lysosomes are example of produced
-receiving proteins and lipids from the ER, modifying them if needed, and then sorting and packaging them into vesicles that are dispatched to their designated locations within or outside the cell

-one side of the apparatus is near the rough ER called the CIS side , it receives the products from ER, then they move into the apparatus
-they move to the opposing side called the TRANS side

-found especially in glandular cells

Question 28

mitochondria

Answer 28

-they have their own DNA, allowing independence in the cell
-has a double membrane
outer=smooth inner= folded into cristae
-inside inner membrane, substance is called matrix
-area between two membranes is called inner membrane
-cristae provides larger surface area of chem reactions
-‘‘powerhouse of cell’’ most reactions produces ATP
-70s ribosomes made and contained on its own

-cells with high energy requirements have a larger number

Question 29

nucleus

Answer 29

-bordered by a double membrane (envelope) which allows compartmentalization where area of DNA can conduct function
-nuclear pores result in not fully isolated
-DNA in form of chromosomes in eukaryotic
-genetic materials of cell is stored and enables traits to be passed on
-when the cell isn’t dividing, chromosomes are not present in visible structures
-no nucleus= no reproduction
-contains a dark area NUCLEIOI where ribosome molecules are manufactured here and pass through nuclear envelop before assembling ribosomes

Question 30

chloroplast

Answer 30

-only found in plants and algae
-contains a double membrane
-contains DNA (in form of rings) and 70s ribosomes
-the interior contains granum, thylakoids and stroma
-a single granium is made from a stacked thylakoids (flattened membrane sacs needed for absorption of light) like coins
-fluid stroma is like cytoplasm and contains enzymes for photosynthesis
-they can reproduce independently

Question 31

centrosomes

Answer 31

only found in animal cells
-consist of pair of centrioles and right angles
-involved in assembly of microtubes which are important for providing structure and cell division
-located at one end of nucleus

Question 32

lysosomes

Answer 32

only found in animal cells
-are digestive centers that arise from Golgi apparatus
-does not have internal structures
-vesicles bounded by single membrane and contains lots of enzymes
-enzymes are hydrolytic and breakdown chemicals
-they fuse with old or damage organelles to break down ‘'’recycling components’
-break down minerals brought in by phagocytosis
-acidic internal conditions needed to hydrolyze large molecules

Question 33

vacuoles

Answer 33

-usually formed in Golgi apparatus
-membrane bound
-in plants occupies large space
-in animals there are many small ones
-store diff substances
-enables high surface to volume ratio

Question 34

simple summary of functions of each organelle

Answer 34

nucleus= contains the DNA
nucleolus= makes ribosome molecules
mitochondria=releases the energy
chloroplast= convert sunlight to sugar
ribosomes= makes proteins
ER= carries proteins/lipids/minerals in pathway
golgi apparatus= packages and ships proteins
lysosomes= breaks stuff down
cell wall= protects/supports cell
cell membrane= controls what enters/ exits
vacuole= storage
cytoplasm=fluid holding organelles
flagella= movement

Question 35

differences in prokaryotic and eukaryotic cells

Answer 35

PROKARYOTIC:
-DNA in forms of rings with no proteins
-DNA free in cytoplasm
-no mitochondria
-70s ribosomes
-no internal compartmentalization
-smaller
EUKARYOTIC:
-DNA with proteins as chromosomes
-DNA is enclosed within nuclear envelope
-mitochondria present
-80s ribosomes
-internal compartmentalization
-larger

Question 36

similarities in prokaryotic and eukaryotic cells

Answer 36

• both have some outside boundaries involving plasma membrane
  -both conduct all functions of life
  -DNA present in both

Question 37

processes of life

Answer 37

ALL ORGANISMS ( MULTI OR UNI ) CARRY OUT THESE FUNCTIONS OF LIFE:

1) metabolism- sum of all chem reactions occurring within an organism
2)growth- development of an organism
3)-reproduction- ability to produce offspring
4)responding to stimuli- as environment changes, so does organism
5)homeostasis- maintenance of internal conditions
6) nutrition- ability to aquire energy/materials needed for life
7)excretion- releasing materials not needed/harmful into environment
8)movement-ability to move/change positions

Question 38

ways that unicellular organisms carry out life functions

Answer 38

homeostasis= cell membrane controls movement of what comes in and out
excretion= vacuoles store waste
response to stimuli= cilia, flagella allow movement
nutrition= vacuoles carry out digestion
growth= ribosomes provide building blocks for growth

Question 39

differences in structure of animals, plant and fungal cells

Answer 39

CELL WALLS
Animal cell do not have a cell wall
Plant cell walls are composed of the polysaccharide cellulose
Fungal cell walls are made up mainly of glucans, chitin and glycoproteins

VACUOLES
present in animal cells but they tend to be small, numerous
Plant cells have large permanent vacuoles used for the storage
Like animal cells, fungal cells can contain vacuoles but they are small and non-permanent

CHLOROPLASTS
Animal cells do not have chloroplasts
Plant cells possess many chloroplasts
Fungal cells do not have chloroplasts

CENTROILES
Animal cells contain centrioles used in the role of microtubule organisation during cell division
Plant cells do not possess centrioles
Fungal cells do not possess centrioles

CILIA/FLAGELLA
Animal cells can have cilia and flagella, associated with a basal body (a protein structure from which the cilia are assembled),
Plant cells do not contain cilia or flagella
fungi do not contain cilia or flagella

Question 40

Atypical cell structures

Answer 40

atypical structure enable them to carry out specialized functions
The number of nuclei can be used to illustrate atypical examples

1)skeletal muscle fibers- groups of cells fuse together to form fibres that are multinucleate with limited nuclear membrane resulting in multiple nuclei

2) phloem tissue- transporting dissolved substances around plant and has no nuclei or mitochondria and supported by companion cell

3) fungal hyphae- Fungi have many long, narrow branches called hyphae. cells are multinucleated with continuous cytoplasm ad cell divides nucleus but doesn’t undergo cytokinesis. No end cell wall makes it appear as one

4) red blood cells- no nucleus=larger volume for oxygen binding

Question 41

theory of endosymbiosis

Answer 41

theory that all eukaryotic cells evolved from a common unicellular ancestor that had a nucleus and reproduced sexually and engulfed the smaller prokaryotes (mitochondria and chloroplast) that could create energy via endocytosis
EVIDENCE:
-same size as most bacterial cells
-can divide by simple binary fission
-has their own DNA which is naked and circular and produce their own ribosomes
-has a double membrane
-has their own transcription and translation

Question 42

differentiation of cells

Answer 42

Every nucleus within the cells of a multicellular organism contains the same genes. because of this, they have a diverse range of functions because during differentiation certain genes are expressed (‘switched’ on)
Whether a gene is expressed or not is triggered by changes in the environment

Question 43

atypical definition

Answer 43

cells that have an abnormal feature not found in usual cells