Cells 3.2 Flashcards
Structure of eukaryotic cells (AO1)
What is a eukaryotic cell?
A cell with a nucleus AND membrane-bound organelles.
Structure of eukaryotic cells (AO1)
Describe the structure of the nucleus (2 marks).
1. Nuclear envelope and pores
OR double membrane and pores;
2. Chromosomes/chromatin
OR DNA wrapped around histones;
3. Nucleolus/nucleoli
Structure of eukaryotic cells (AO1)
Describe the function of the nucleus (2 marks).
1. Stores genetic information/material for polypeptides (production)
OR codes for proteins
OR codes for primary structure of polypeptides;
2. Site of (Semi-conservative) DNA replication;
3. Production of mRNA/tRNA
OR site of Transcription;
4. Production of rRNA/ribosomes;
Structure of eukaryotic cells (AO1)
Eukaryotic cells contain linear DNA which is bound to which protein?
Histones
Structure of eukaryotic cells (AO1)
Draw out and label the structure of a mitochondrion
Structure of eukaryotic cells (AO1)
Mitochondrial DNA is linear OR circular?
Circular
Structure of eukaryotic cells (AO1)
What size are mitochondrial ribosomes?
70S
This is smaller than cytoplasmic ribosomes which are 80S
Structure of eukaryotic cells (AO1)
What process takes place in the mitochondria
Aerobic respiration
Structure of eukaryotic cells (AO1)
What are the products of aerobic respiration?
Carbon dioxide, water AND ATP
Structure of eukaryotic cells (AO1)
The cristae provide a large _________ _________ so more ATP synthase can be embedded into the inner mitochondrial membrane.
surface area
Structure of eukaryotic cells (AO1)
Which organelle can be found on the outer surface membrane of the rough endoplasmic reticulum?
Ribosome
Structure of eukaryotic cells (AO1)
What is the function of the rough endoplasmic reticulum?
Provide a large surface area for the synthesis of proteins via ribosomes on their surface.
Packages proteins into vesicles to be transported to the Golgi apparatus
Structure of eukaryotic cells (AO1)
Why is the smooth endoplasmic reticulum ‘smooth’?
No ribosomes on its surface
Structure of eukaryotic cells (AO1)
What is the function of the smooth endoplasmic reticulum?
- Synthesise lipids and packages them into vesicles.
- Synthesise carbohydrates and packages them into vesicles.
Structure of eukaryotic cells (AO2)
1. Less phospholipids in rough
OR
More protein/glycoprotein in rough
OR
Presence of ribosomes in rough;
2. (More protein/glycoprotein/ribosomes)
Rough – production/transport of proteins;
3. (More phospholipid)
Smooth –production / modification / packaging / transport of lipids
Structure of eukaryotic cells (AO1)
What is the function of the Golgi apparatus?
1. Sorts, modifies and packages proteins into vesicles.
E.g. adds a carbohydrate to a protein to form a glycoprotein.
E.g. forms chylomicrons
2. Forms lysosomes
Structure of eukaryotic cells (AO1)
What is the name of enzyme contained by lysosomes?
Hydrolytic enzymes
(aka lysozymes)
Structure of eukaryotic cells (AO1)
Describe how lysosomes destroy pathogens or damaged organelles (2 marks).
- Lysosomes fuse with vesicle
- Release its hydrolytic enzymes
- Which breakdown pathogens AND/OR damaged and worn out organelles
Structure of eukaryotic cells (AO1)
What is the function of ribosomes?
Synthesise proteins
Structure of eukaryotic cells (AO1)
Ribosomes are made up of……..
ribsomal RNA (rRNA)
Protein sub-units
Structure of eukaryotic cells (AO1)
What size are cytoplasmic ribosomes?
80S
This is also the size of ribosomes on the rough ER
Structure of eukaryotic cells (AO1)
Eukaryotic cells produce and release proteins. Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells (4 marks).
- DNA in nucleus is code (for protein);
- Ribosomes/rough endoplasmic reticulum synthesis protein;
- Mitochondria produce ATP (for protein synthesis);
- Golgi apparatus modifies and packages protein;
- Vesicles transport protein
OR
- (Vesicles) fuse with cell(-surface) membrane;
Accept exocytosis at cell membrane
Structure of eukaryotic cells (AO1)
What is the name of the process when a vesicle fuses with the cell surface membrane to release its content?
Exocytosis
Structure of eukaryotic cells (AO1)
TRUE or FALSE
The nucleus can contain more than one nucleoli?
TRUE
Structure of eukaryotic cells (AO1)
DNA in the eukaryotic nucleus is linear OR circular?
Linear
Structure of eukaryotic cells (AO1)
The cell-surface membrane consists of a _________________.
Phospholipid bilayer
Structure of eukaryotic cells (AO1)
Name the main polymer that forms the cell wall in plants.
Cellulose
Structure of eukaryotic cells (AO1)
Name the main polymer that forms the cell wall in fungi.
Chitin
Structure of eukaryotic cells (AO1)
Draw out and label the structure of a chloroplast.
Chloroplasts also contain circular DNA, 70S ribosomes & starch grains.
Structure of eukaryotic cells (AO1)
The thylakoid membranes provide a large surface area for more ______________.
chlorophyll
this allows MORE light energy to be absorbed during photosynthesis
Structure of eukaryotic cells (AO1)
The synthesis of glucose as a result of photosynthesis takes place in which part of the chloroplast?
Stroma
Structure of eukaryotic cells (AO1)
Name the main polymer that forms the cell wall in algae.
Cellulose
Structure of eukaryotic cells (AO1)
Algae are unicellular eukaryotic organisms that can ________________ .
Photosynthesise
Structure of eukaryotic cells (AO1)
What is the function of the large permanent vacuole in plant cells?
- Provide support, making cells turgid.
- Store of sugars and amino acids
Structure of eukaryotic cells (AO2)
U. marinum cells ingest bacteria and digest them in the cytoplasm.
Describe the role of one named organelle in digesting these bacteria (3 marks).
1. Lysosomes;
2. Fuse with vesicle;
3. (Releases) hydrolytic enzymes;
Structure of eukaryotic cells (AO2)
Give one feature of the chloroplast that allows protein to be synthesised inside the chloroplast and describe one difference between this feature in the chloroplast and similar features in the rest of the cell.
Mark in pairs, 1 and 2 OR 3 and 4
- DNA;
- Is not associated with protein/histones but nuclear DNA is
OR is circular but nuclear DNA is linear
OR is shorter than nuclear DNA;
- Ribosomes;
- Are smaller (70S) than cytoplasmic ribosomes;
Structure of eukaryotic cells (AO1)
Outline the similarities in the structures of chloroplasts and mitochondria.
1. Both double membrane;
2. Both contain (circular) DNA;
3. Both contain ribosomes;
Structure of eukaryotic cells (AO1)
Outline the differences in the structures of chloroplasts and mitochondria.
4. Chloroplasts have thylakoids/grana whereas mitochondria have cristae;
5. Chloroplasts stroma whereas mitochondria matrix;
6. Chloroplasts pigments (chlorophyll) whereas no pigments in mitochondria;
7. Chloroplasts have starch grains whereas mitochondria have no starch grains;
Structure of eukaryotic cells (AO1)
D - Granum/grana/thylakoid(s);
E - starch / lipid;
Structure of eukaryotic cells (AO1)
B;
A;
E;
Structure of eukaryotic cells (AO2)
Human breast milk is produced and secreted by gland cells. These gland cells have adaptations that include many mitochondria and many Golgi vesicles. The milk contains a high concentration of protein.
Explain the role of these cell adaptations in the production and secretion of breast milk (2 marks).
- (Many mitochondria) release energy / ATP for movement of vesicles / synthesis of protein / active transport;
- (Many Golgi) vesicles transport protein / glycoprotein / milk to cell membrane / out of cell;
Structure of eukaryotic cells (AO1)
Structure of eukaryotic cells (AO1)
B Golgi (body / apparatus);
C Mitochondria / mitochondrion;
Structure of eukaryotic cells (AO1)
Name two structures present in plant cells that are not present in animal cells.
- Chloroplasts
- Cell wall
- Cell vacuole
- Starch grains
Structure of eukaryotic cells (AO1)
A stroma
B granum
Structure of eukaryotic cells (AO1)
W – chloroplast, photosynthesis;
Z – nucleus, contains DNA / chromosomes / holds genetic information of cell.
Structure of eukaryotic cells (AO1)
Identify X
Crista/cristae
Structure of eukaryotic cells (AO1)
L
H
N
Structure of eukaryotic cells (AO2)
Membrane-bound organelle(s)
OR Mitochondrion/mitochondria
OR Vesicle(s)/lysosomes
OR Rough endoplasmic reticulum
OR Nucleus/(double) nuclear membrane/pore(s)/ nuclear envelope;
Structure of eukaryotic cells (AO1)
Define a tissue
Similar specialised cells that perform a specific function
Structure of eukaryotic cells (AO1)
Define an organ
Different tissues that work together to perform a specific / vital function
Structure of eukaryotic cells (AO1)
Define an organ system
Different organs that work together to perform a specific / vital function
Structure of eukaryotic cells (AO1)
In complex multicellular organisms, eukaryotic cells become _____________ for specific functions.
specialised
Structure of prokaryotic cells and of viruses (AO1)
Prokaryotic cells are smaller OR larger than eurkaryotic cells
Smaller
Structure of prokaryotic cells and of viruses (AO1)
Define a prokarytic cell
Cells that DO NOT contain a nucleus or membrane-bound organelles
Structure of prokaryotic cells and of viruses (AO1)
Describe the structure of DNA in prokaryotic cells
no nucleus;
single circular DNA molecule that is free in the cytoplasm;
not associated with proteins/histones;
Structure of prokaryotic cells and of viruses (AO1)
By what process do prokarytic cells replicate their DNA
Semi-conservative replication
Meselson & Stahl used E.coli (a bacteria) for their experiments
Structure of prokaryotic cells and of viruses (AO1)
What is the name of the glycoprotein that makes up the prokaryote cell wall?
Murein
(aka peptidoglycan)
Structure of prokaryotic cells and of viruses (AO1)
What size are prokaryotic ribosomes?
70S
This is smaller than cytoplasmic ribosomes in a eukarytic cell
Structure of prokaryotic cells and of viruses (AO1)
What is the extra source of DNA called in a prokaryote
Plasmid(s)
Structure of prokaryotic cells and of viruses (AO1)
What genes are typically found in plasmids
Genes that benefit prokaryote survival
e.g., antibiotic resistance
Structure of prokaryotic cells and of viruses (AO1)
TRUE or FALSE
Prokaryotes can have more than one plasmid
TRUE
Prokaryotes have a variable number of plasmids
Structure of prokaryotic cells and of viruses (AO1)
What structure often surrounds the prokaryotic cell?
Capsule
Structure of prokaryotic cells and of viruses (AO1)
Give two structures found in all prokaryotic cells and in all eukaryotic cells.
- Cell(-surface) membrane;
- Ribosomes;
- Cytoplasm;
- DNA;
Structure of prokaryotic cells and of viruses (AO1)
Name two structures found in all bacteria that are not found in plant cells.
- Circular DNA (molecule in cytoplasm);
- Murein cell wall
OR Peptidoglycan cell wall
- Smaller/70S ribosomes in cytoplasm;
Structure of prokaryotic cells and of viruses (AO1)
Name two features of HIV particles that are not found in bacteria.
- Capsid;
- Reverse transcriptase;
- RNA genome;
Accept ‘genetic material’ OR ‘genes’ for ‘genome’
- Envelope;
- Attachment proteins
Structure of prokaryotic cells and of viruses (AO1)
TRUE or FALSE:
All prokaryotic cells have one or more flagella.
FALSE
Some prokaryotes have NO flagella
Structure of prokaryotic cells and of viruses (AO1)
All prokaryotic cells have ___________ ribosomes than eukaryotic cells.
smaller
Structure of prokaryotic cells and of viruses (AO1)
Flagellum
Structure of prokaryotic cells and of viruses (AO1)
Name an organelle found in both a chloroplast and a prokaryotic cell.
(70S) Ribosome
Structure of prokaryotic cells and of viruses (AO1)
Structure of prokaryotic cells and of viruses (AO1)
Second box ticked
B – statements 1, 2 and 4
Structure of prokaryotic cells and of viruses (AO1)
W – (cell surface) membrane
X – cell wall
Y – capsule
Z – flagellum
Structure of prokaryotic cells and of viruses (AO1)
Viruses are ________ and non-living.
acellular
This means they need a host cell to surivive and reproduce
Structure of prokaryotic cells and of viruses (AO1)
TRUE or FALSE
Prokaryotes can have one or more flagella.
TRUE
Structure of prokaryotic cells and of viruses (AO1)
Draw out and label the key structures of a virus
Structures in red, funtion in black
Structure of prokaryotic cells and of viruses (AO1)
What is the function of the capsid in a virus?
Protects the viral genome (DNA or RNA)
Structure of prokaryotic cells and of viruses (AO1)
What is the function of the viral genome (DNA or RNA)?
Codes for (viral) protein
Structure of prokaryotic cells and of viruses (AO1)
RNA viruses (e.g. HIV) contain an enzyme that converts viral RNA into (c)DNA - what is the name of this enzyme?
Reverse transcriptase
Structure of prokaryotic cells and of viruses (AO1)
What is the function of viral attachment proteins?
Binds to receptors (on cell);
Structure of prokaryotic cells and of viruses (AO1)
TRUE or FALSE
Some viruses contain RNA as their genetic material
TRUE
These are called RNA viruses or retroviruses e.g. HIV
Structure of prokaryotic cells and of viruses (AO1)
Capsid and attachment protein
Methods of studying cells (AO1)
What are the principles of light (aka optical) microscopy?
A thin specimen is illuminated with light;
This light is focussed using a glass lens;
Magnified and view using the eye piece and objective lenses;
Specimens can be alive or dead;
Cellular structures like the nucleus can be stained with dyes to make them visible;
Methods of studying cells (AO1)
Explain why it is not possible to identify smaller organelles like mitochondria using an optical microscope (2 marks).
- Wavelength of light is (too) long;
- So has a lower resolution
Methods of studying cells (AO1)
A section/slice (so nucleus in another part of cell)
OR
(Nucleus) not stained;
A cell is 3D so slicing across the top or bottom may miss the nucleus
Methods of studying cells (AO1)
Identify organelles S and T
S = Vacuole
T = Chloroplast;
Methods of studying cells (AO1)
Give one advantage of viewing a biological specimen using a transmission electron microscope compared with using a scanning electron microscope (1 mark).
Higher resolution
OR
View internal structures;
Methods of studying cells (AO1)
A biologist separated cell components to investigate organelle activity. She prepared a suspension of the organelles in a solution that prevented damage to the organelles.
Describe three properties of this solution and explain how each property prevented damage to the organelles (3 marks).
1. (Ice) cold to prevent/reduce enzyme activity;
2. Buffered to prevent denaturing of enzyme/protein;
3. Same water potential/ Ψ to prevent lysis/bursting (of organelle);
Accept: isotonic for same water potential.
Methods of studying cells (AO2)
Scientists investigated the role of a protein called CENP-W in mitosis. Their method involved cell fractionation and ultracentrifugation.
(a) The scientists began by lysing (breaking open) cells and organelles using a detergent that dissolves lipids in water.
Suggest how the detergent releases CENP-W from cells (2 marks).
- Cell surface membranes made from phospholipid bilyar;
- (Detergent) dissolves membranes / phospholipid (bilayer);
Methods of studying cells (AO2)
Explain how ultracentrifugation separates a protein involved in mitosis CENP-W from other molecules.
- Spin (liquid / supernatant) at (very) high speed;
- Molecules / CENP-W separates depending on (molecular) mass / size / density;
Densest molecules/organelles found at bottom of tube.
Methods of studying cells (AO1)
Contrast how an optical microscope and a transmission electron microscope work (3 marks).
- TEM use electrons whereas optical use light;
- TEM focuses using magnets whereas optical uses (glass) lenses;
- TEM allows a greater resolution;
- (So with TEM) smaller organelles / named cell structure (e.g. mitochondria) can be observed
Methods of studying cells (AO1)
Contrast the limitations of an optical microscope and a transmission electron microscope when studying cells (3 marks).
- TEM view only dead / dehydrated specimens whereas optical (can) view live specimens;
- TEM does not show colour whereas optical can;
- TEM requires thinner specimens;
- TEM requires a more complex/time consuming preparation;
Methods of studying cells (AO1)
During cell fraction explain why biologists use a blender and then filtered the mixture (2 marks).
- Break open cells / homogenise;
- Remove unbroken cells / larger debris;
Methods of studying cells (AO1)
Name the organelle that made up most of the first pellet after centrifuging at a lowest speed.
Nucleus / nuclei;
Methods of studying cells (AO1)
Describe how a sample of chloroplasts could be isolated from leaves (4 marks).
- Break open cells/tissue and filter
Accept homogenise and filter
- In cold, isotonic, buffered solution;
- Centrifuge/spin and remove nuclei/cell debris;
- (Centrifuge/spin) at high(er) speed, chloroplasts settle out;
Methods of studying cells (AO1)
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope (3 marks).
- Add drop of water to (glass) slide;
- Obtain thin section (of plant tissue) and place on slide / drop of water;
- Stain with / add iodine in potassium iodide.
- Lower cover slip using mounted needle.
Allow any appropriate method that avoids trapping air bubbles
Methods of studying cells (AO1)
A student investigated the distribution of stomata on leaves from two species of plant. She removed small pieces from the lower surface of the leaves of each plant species. She mounted these pieces on separate microscope slides. She then counted the number of stomata in several parts of the epidermis on each piece of leaf tissue using an optical microscope.
The pieces of leaf tissue examined were very thin.
Explain why this was important.
- Single layer(s) of cells;
- So light can pass through;
Methods of studying cells (AO1)
A student investigated the distribution of stomata on leaves from two species of plant. She removed small pieces from the lower surface of the leaves of each plant species. She mounted these pieces on separate microscope slides. She then counted the number of stomata in several parts of the epidermis on each piece of leaf tissue using an optical microscope.
Give two reasons why it was important that the student counted the number of stomata in several parts of each piece of leaf tissue.
- Distribution may not be uniform
OR so it is a representative sample;
- To obtain a (reliable) mean;
Methods of studying cells (AO1)
Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells (5 marks).
- Cell homogenisation to break open cells;
- Filter to remove (large) debris / whole cells;
- Use isotonic solution to prevent osmotic damage to mitochondria / organelles;
- Keep cold to prevent / reduce damage by enzymes / use buffer to prevent protein / enzyme denaturation;
- Centrifuge at lower speed to separate nuclei / cell fragments / heavy organelles;
- Re-spin (supernatant / after nuclei / pellet removed) at higher speed to get mitochondria in pellet / at bottom.