B1 & B2.1 - Cells & Cell Division Flashcards
What are the main characteristics of an Animal Cell?
Nucleus, Cytoplasm, inelastic, partially-partially-permable Cell Membrane, Mitochondria, Ribosomes
Cytoplasm
Liquid gel where organelles are suspended. This is where most of the chemical reactions needed for life take place.
Nucleus
Controls all the activities of the cell that contains genetic material, which carry instructions for making proteins needed to build new cells / organisms.
What are the main characteristics of a Plant Cell?
Components of an Animal Cell + Chloroplasts, Permanent Vacuole and Cellulose Cell Wall.
Cell Membrane
Controls passage of substances into the cell (glucose and mineral ions), as well as movement out of the cell (urea and hormones).
Mitochondria
Where aerobic respiration takes place, releasing energy for the cell.
Ribosomes
Where protein synthesis takes place, making all the proteins needed in the cell.
True or False?
Plant Cells do not contain all the characteristics of an animal cell (cell membrane, cytoplasm etc.)
False!
Plant Cells have all the features of a typical animal cell, but they also contain features that are needed for their very different functions.
True or False?
All plant and algal cells have a cell wall made of cellulose that strengthens the cell and gives it support.
True.
Chloroplasts
Contains chlorophyll, which makes chloroplasts green! Chlorophyll absorbs light for photosynthesis.
Permanent Vacuole
A space in the cytoplasm filled with cell sap. Important for keeping the cells rigid to support the plant.
True or False?
A plant cell has many features in common with an animal cell, as well as other features that are unique to plants.
True!
Plant Cells have added features, such as chloroplasts and a permanent vacuole.
True or False?
Roots cell contain chloroplasts because they are underground and need to photosynthesise.
False!
Because they are underground, they cannot absorb sunlight; a key component in producing their own food through photosynthesis. As a result, they do not have chloroplasts!
Define Prokaryotic
Pro- = Before / None
- kary- = Karyon = Nucleus
- Otic = State / condition
= A cell in which their genetic material is encased WITHOUT a nucleus, thus freely moving around in the cell.
Define Eukaryotic.
Eu - “Eureka” = True / Aha!
- kary- = Karyon = Nucleus
- Otic = state / condition of an entity
= A cell which has their genetic material encased WITH a nucleus.
Give an example of a Prokaryotic Cell.
Bacteria
Give an example of a Eukaryotic Cell.
Animal and plant cells!
What is a Eukaryotic cell?
Cells which all have a cell membrane, cytoplasm, and genetic material that is enclosed in a nucleus.
What is a Prokaryotic cell?
Much like eukaryotic cells, except their genetic material that is NOT enclosed in a nucleus, and may also contain extra small rings of DNA called plasmids.
What are plasmids?
Located usually in Prokaryotic cells (e.g. Bacteria), DNA which are codedfor very specific features such as antibiotic resistance.
What is a flagellum?
A long protein strand that lashes about to allow the cell to move around.
What effect does bacteria have on other organisms.
Little to no effect. Many are very useful.
Diffusion
Net movement of particles from an area of high concentration to an area of low concentration.
Effect of Diffusion
Usually results in equilibrium; same number of particles on each side.
Net Movement
Net movement = particles moving in - particles moving out
Why Diffusion is Passive
Doesnt need energy: particles move down the concentration gradient easily.
Factors affecting Diffusion
• Temperature:
higher temperature = more kinetic energy for particles to richochet/bounce off each other.
- Particles move around quicker consequently.
• Steeper Concentration Gradient:
Steeper gradient = greater net movement of particles.
Active Transport
Moving UP / against a concentration gradient, which needs energy.
Examples of Active Transport
• Nerve Cells:
Active transport of Sodium moving out and Potassium moving in the nerve cell.
• Root Hair Cells:
Magnesium ions actively transported into the root hair cell.
Difference between Active Transport & Diffusion
- ATP (adenosine triphosphate) is needed for Active Transport.
- Active Transport is going against the concentration gradient; lower concentrated particles moving to an area of higher concentration.
- Diffusion doesn’t need energy.
- Diffusion goes down the concentration gradient; higher concentrated particles moving to an area of lower concentration.
ATP
Adenosine Triphosphate
Adenosine
Tri-
Phosphate
Carrier proteins
Special proteins that span a cell membrane width.
Molecules that a cell needs will bind with the carrier proteins.
As a result, ATP is needed to change or rotate the proteins if needed.
Isotonic solution
External concentration of solutes [outside the cell] = Internal concentration of solutes [inside the cell]
Hypertonic
External concentration of solutes [outside the cell] > Internal concentration of solutes [inside the cell]
Hypotonic
External concentration of solutes [outside the cell] < Internal concentration of solutes [inside the cell]
Cell Differentiation
The process for when a cell changes to become specialised for its role.
Partially-permeable membrane
Membrane with tiny holes which allows small molecules to pass through, except large molecules.
Undifferentiated cells
Stem cells
Specialisation of Sperm Cells
Reproduction:
- long tail-like flagellum and streamlined head to help it swim to the egg cell.
- plentiful mictochronfria to provide needed energy
- Enzymes in the head to digest through egg cell membrane.
Specialisation of Nerve Cells
Rapid signalling:
- long length to cover more distance and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.
Specialisation of Muscle Cells
Contraction:
- long lengths for space to contract
- lots of mitochrondria to generate energy needed for contraction.
Specialisation of Root Hair Cells
Absorbing water & minerals:
- long hair-like tube that stick out into the soil for a big surface area to absorb water and mineral ions.
Most differentiation occurs…
…As an organism develops.
Cells that differentiate in mature animals…
…Are mainly used for repairing and replacing cells, such as skin and blood cells.
Specialisation of Phloem & Xylem Cells
Transporting Substances:
- form phloem and xylem tubes respectively to transport food and water around plants.
- to make these tubes, the cells are long and joined end-to-end.
- Xylem tubes are hollow in centre,
- Phloem have very few subcellular structures, so substances can flow through them.
Turgor
The pressure that builds up when the inelastic cell wall of a plant cell resists expansion, and the cell becomes rigid or turgid.
Plasmolysis
When water is lost from a plant cell through osmosis ie cells in a hypertonic solution;
- the cell membrane pulls away from the cell wall.
Why Osmosis is needed for turgor
Osmosis is key to maintaining turgor in plant cells, as it needs a rigid structure to protect their sub-cellular components.
Difference(s) between Diffusion and Active Transport.
Active transport uses ATP ( Adenosine Triphosphate ), diffusion uses no energy - therefore active transport is active, diffusion is passive.
What is osmosis, really?
The diffusion of water molecules.
Why do animal cells, which are hypotonic, burst?
The cell membrane is not elastic enough to contain all the water.
- Animal cells also don’t have cell walls, which plant cells have to keep their turgor.
How do people die from ecstasy through water consumption?
Their animal cells, receiving an abnormal amount of water, become hypotonic. As a result, they burst.
- The killing blow is due to brain cells becoming hypotonic and likewise, bursting. This kills the person.
Water Potential
The measure of the tendency of the concentration % of water molecules to diffuse to another area.
[Synoptic Link] Water potential, Pure Water, and Isotonic Solutions ( 1 / 2 )
- Pure water has a water potential of 0, meaning water molecules will not diffuse to another area.
- Similarly, in an isotonic solution, because the concentration of solutes are equal both internally in the cell and externally in the solution, water molecules will not diffuse to either area.
[Synoptic Link] Water potential, hypertonic & hypotonic solutions ( 2 / 2 )
- Water Potential measures the tendency of water molecules to diffuse to another area because of the concentration of solutes present internally [ in the cell ] and externally.
- Within a hypertonic solution, because more solutes are present externally in the solution than internally inside the cell, water molecules will diffuse out the cell and into the solution.
- In a hypotonic solution, more water molecules are present [than solutes] outside the cell in the solution than inside the cell, so water molecules diffuse into the cell.
Negative number quantities in Water Potential
The greater the negative number is in reference to water potential in a solution or specimen, the less pure it is.
- Thus, more solutes are present.
[Synoptic Link] Pure Water and Water Potential
Pure water has a water potential of zero; water molecules will not diffuse to another area.
Lysis; Hypotonicity
When a cell fills with water. Since the cell membrane is inelastic, the cell will burst unless it has a cell wall. The cell becomes lysed when it is exposed to a hypotonic solution.
Crenation ; Hypertonicity
When water floods out an animal / body cell. The cell becomes crenated when it is exposed to a hypertonic solution.
[Exchanging Materials] Unicellular organisms
- High surface area : volume ratio.
- Can exchange materials directly with their environment through their cell membrane ( which is partially permeable! ).
[Exchanging Materials] Multicellular organisms
- Low surface area : volume ratio.
- The surface areas of multicellular organisms aren’t large enough to exchange materials directly with their environment.
- Consequently, they’ve evolved to be equipped with specially-adapted exchange surfaces and transport systems.
Multicellular organisms’ evolutions examples for specially-adapted exchange surfaces and transport systems
Humans:
- Lungs and the Alveoli
Fish:
- Gills
Root Hair Cells
The Cell Cycle: phases
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase
- Cytokenesis
Interphase, Prophase, …?…, Anaphase, Telophase, Cytokenesis.
What phase is missing?
Interphase, Prophase, METAPHASE, Anaphase, Telophase, Cytokenesis.
[1] , [2] , [3] , Anaphase , [5] , [6] .
What’s missing?
INTERPHASE , PROPHASE , METAPHASE , Anaphase, TELOPHASE , CYTOKENESIS.
… Anaphase , [5] , [6] .
What’s missing?
Anaphase, TELOPHASE , CYTOKENESIS
Phases of the Cell Cycle:
[1] , [2] , [3] , [4] , [5] , [6] .
Complete the missing steps.
Hint: ___phase, ___phase etc.
[1] Interphase [2] Prophase [3] Metaphase [4] Anaphase [5] Telophase [6] Cytokenesis
Well done if you remember!
Mitosis
The main stage(s) at which a cell divides:
[3] Metaphase - The replicated chromosomes line up along the centre of the cell.
[4] Anaphase - The spindle fibres contract, and the chromosomes are pulled to opposites poles equally.
[5] Telophase - Cell membranes form around each of the sets of chromosomes, dividing the nucleus, and creating two new nuclei.
[6] Cytokenesis - The original cell has been fully divided into two daughter cells, both having identical DNA to each other and to the parent cell.
[1] Interphase
DNA inside the cell is replicated to from copies of each chromosome and synthesis of new sub-cellular structures.
[2] Prophase
DNA replication has occurred by now, and each chromosome is identical. The spindle fibres move to opposite sides of the cell.
[4] Anaphase
The spindle fibres contract, and the chromosomes are pulled to opposites poles equally.
[3] Metaphase
The replicated chromosomes line up along the centre of the cell.
[5] Telophase
Cell membranes form around each of the sets of chromosomes, dividing the nucleus, and creating two new nuclei.
Are Interphase and Prophase part of mitosis?
No.
[1] Interphase - DNA is replicated, not divided.
[2] Prophase - DNA replication has occurred by now, and each chromosome is identical. But the DNA isn’t divided yet.
Note: Prophase is when the DNA replication has finished which happened in the Interphase.
[6] Cytokenesis
The original cell has been fully divided into two daughter cells, both having identical DNA to each other and to the parent cell.
