Cell Structure And Cell Cycle Flashcards
PMATC
Prophase metaphase anaphase telophase cytokinesis
Prophase
Chromatin condenses and chromosomes become visible
Nucleoli disappears
Nuclear membrane disappears
Centrioles move to poles of cell to form spindle fibres called kinetichore
Chromosomes attach to spindle fibres at centromere.
Metaphase
Chromosomes (made up of two sister chromatids) line up on the equator of spindle fibres
The microtubules of the spindle are attached to the centromere of each chromosome
Centrioles are different from centromeres
Centriole floats in nucleoplasm and forms spindle when needed
Centromeres of chromosome attach to spindle microtubules
Anaphase
Centromeres divide and spindle fibres begin to shorten
Sister chromatids are pulled to opposite poles by spindles using energy from ATP (produced by mitochondria)
Separated chromatids are referred to as separate chromosomes.
Telophase
Chromosomes reach poles
Chromosomes decondense so are no longer visible
Spindle breaks down and centrioles reappear
Nuclear membrane reappears
Nucleoli reappear
Cytokinesis
Cytoplasm splits along with cell membrane and nucleus.
Chromosomes,chromatin,chromatid difference
Chromatin - decondensed, unravelled, before mitosis in interphase and semi conservative replication.
Chromosomes are only seen during cell division
Chromatid is one dna molecule and two form a chromosomes
Called chromatids as soon as chromatin condenses.
mitotic Index
% of cells in mitosis
Mitosis is a controlled process because
There are four checkpoints:
G0 = resting state
G1= check for nutrients,growth factors and dna damage
Then S is dna synthesis
Then G2 is check for cells size and dna replication
Then metaphase checkpoint checks for chromosome spindle attachment
Then G1 begins
Cyclin proteins control the cell cycle
Apoptosis is
Programmed cell death
Cyclin proteins
Control the cell cycle
Tumours and cancers are formed by
Uncontrolled cell division
How to treat cancer
Chemotherapy is the injection of drugs that inhibit DNA replication/ spindle formation for example colchacine
Binary fission is cell for what type of cells
Prokaryotes like bacteria
What is binary fission
Replication of circular DNA and plasmids
Then the division of cytoplasm to produce two daughter cells
How do bacterial cells multiply and give formula to find the number of cells (N) after (n) generations (N0 is initial number at time 0)
N=N0x2^n
Exponentially
Embryonic/Adult stem cells
Early embryo (four days) Unspecialised cells undergo differentiation to become specialised. All contain the same genetic information but different genes are expressed differently.
Specialised cell
Gene expression causes cell specialisation
Differences between meiosis and mitosis
Meiosis = 4 genetically different daughter cells whereas mitosis produces two genetically different daughter cells
Meiosis produces gametes for sexual reproduction
Mitosis is for growth/repair/sexual reproduction
Mitosis has 46 chromosomes and are diploid
Meiosis produces 23 chromosomes hence haploid that become diploid when fuses with opposite gamete
Meiosis has two divisions of cytoplasm in one cycle whereas mitosis only has one
How is skin surface replaced after sloughing
Adult stem cells replace cells lost
Golgi vesicles function
Store and transport lipids and proteins made by the golgi apparatus
Golgi vescicle structure
Phospholipid bilayer (double membrane)
Lysosomes are
Tiny sac of digestive enzymes, surrounded by a single membrane
Function of lysosomes
Hydrolyse material ingested by phagocytes
Exocytosis release enzymes to the outside of cells and destroy material around the cell
Digest worn out organelles so useful chemicals can be used
Autolysis = cells broken down completely after they have dies
What is autolysis
Complete break down of cells after they have died
Exoctyosis
Bulk transport of material out of cell using vesicles
Endocytosis
Bulk transport of material into cell using vesiclese
What does the endoplasmic reticulum look like
Made up of flattened membrane bound sacs called cisternae
What is on the surface of rough ER
Ribosomes
What does the rough ER do
Modifies and transports proteins made from the ribosomes
Function of smooth ER
Suthesis and processes lipids
Smooth ER in liver cells do what?
Break down toxins
What is multicellularity
Division of labour between cells
What is a tissue
One type of specialised cells
What is an organ
Severa, tissues
What is blood 🩸
A tissue
What does the golgi look like
Unstable structure = constantly changing
Stacks of membrane bound flattened sacs
What does the golgi do
Receives proteins from ER Modifies proteins Processes and packages them into vescicle Vesicles are moved to plasma membrane Exocytosis
Also add carbohydrates to proteins to form glycoproteins Produce secretary enzymes Secrete carbs Form lysosomes Transport modify and store lipids
Plant Cell wall looks
Like and function
Line (middle lamedla is the junction of two cell walls)
Provides rigidity and strength to the cell to prevent bursting under pressure created by osmotic entry of water
plant cell is made opus of what which is a what
Cellulose
Polysaccharide
Cell wall of algae
Cellulose/glycoproteins
Cell wall of fungi
Chitin polysaccharide
Vacuole function and look alike
Fluid filled sac bound by a single membrane called tonoplast
Support to plant cells
Temporary food store
Pigments may colour petals to attract pollinating insects
Ribosomes are, —-,size,which is found where and what does it look like and do
Small cytoplasmic granules Found in all cells Two types 80S which is around 25nm in eukaryotes and 70S which is slightly smaller and in prokaryotes Two subunits - one large and one small Ribosomal RNA and protein in both Protein synthesis
Prokaryotic organisms description
Unicellular, no nucleus or membrane bound organelles like bacteria or archaea
Eukaryotes did what after prokaryotes
Evolved - are more evolved
Prokaryotes cell wall made of
Muréin for shape and protection
What is a messasome, it’s purpose and where is it found
Inward folded piece of membrane
Increases SA for reactions
Found in eukaryotes
Prokaryotes contain what organelles
Flagellum for movement
Pillí - movement and adherence to surfaces
Slime capsule - stop invading phagocytes
70S ribosomes
Cytoplasm
Cell membrane
Cell wall
Double stranded dna and nuclei of containing GM in circular loops called plasmids
Bacteria contain plasmids purpose
Useful for genetic engineering
Extra chromosomal dna
Nucleus
10 micrometers to 20 micrometers Nuclear envelope Nuclear pore Nucleoplasm Chromosomes Nucleolus
Nuclear envelope
Double membrane
Outer is continuous with ER
Controls and regulate movement of in and out of organelle
Nuclear pores
Allows passage of large molecules like RNA around 300nm
Nucleoplasm
Jelly like material that makes up bulk of nucleus
Nucleoli
Manufacture ribosomal RNA and assembles ribosomes
What is magnification
How much bigger an image is to reality
What is resolution
The smallest distance an visible between two dots
How does a light microscope work
Rays of light hit specimenand are seen through eyepiece
Pros of light microscope
Easy and cheap to operate
Living specimens as well
Cons of optical microscope
Low resolution and magnification - can’t see organisms smaller than 0.2 micrometers
Specimens often need staining to show specific organelles
Long wavelength of light rays mean
Smaller organelles aren’t visible
Two types of electron microscope
Transmission
Scanning
How do transmission electron microscope work
Use electromagnets to focus a beam of electorons which are then transmitted into specimen
Denser parts absorb more electrons hence appear darker in black and white image
Max resolution for transmission electron microscope
0.1nm
Max resolution transmission electron microscope
10,000,000
Pro of transmission electron
Highest resolution and magnification
4 cons of TEM
Non living matter 2D black and white Staining of heavy metals hence artefacts may form Vacuum Elebaorate staining
How does scanning electron microscope work
Scan beam of electrons across specimen and knock electrons off it
Electrons gather in cathode ray tube to form image
Max magnification of SEM
30,000
Max resolution of SEM
20nm
3 pros of SEM
Complex 3D images are formed
Works on their specimens
Higher msg and res than light microscope
3 cons SEM
Large expensive hard to operate
Mounted in vacuum
Has to be dead specimen
Image equation
Image = actual x magnification
Cell fractionation steps
Tissue is cut up and kept in a cold isotonic buffered isolation medium (solution)
Then further broken in homogeniser
Then spun in ultracentrifuge for 10 mins at low speed
Súpernatant is removed and pellet is spun at medium speed then higher speed to obtain sediment of chloroplast
What are the isolation mediums have three requirements and why
Cold = slows enzyme action
Isotonic (same water potential) = keeps membrane stable so no bursting or shrivelling
Buffered = keeps ph stable
3 condensed steps cell fractionation
Homogenisation
Filtration
Ultracentrifugation
Eukaryotic cells vs prokaryotic cells
Nucleus vs no nucleus but has plasmids instead HISTONE ASSOCIATE DNA VS DNA introns vs no introns so no splicing Membrane bound organelles vs no membrane bound organelles No Slime capsule vs slime capsule Chloroplasts vs no chloroplast No pilli vs pilli Sometimes flagellum vs sometimes flagellum Either unicellular or multi vs only uni Big vs small 80S ribosomes vs 70S ribosomes Chromatin vs no chromatin Cellulose cell wall vs murein cell wall No mesasome vs mesasome
Why is dna in bacterium called naked
No chromatin
Endosymbiosis theory
Eukaryotes evolved from a prokaryotic ancestor
Endosymbiosis theory stages examples
Ancestral prokaryote, infolding of plasma membrane creates a compartment for nucleoid which is likely to be Arachaea
Then aerobic bacteria is consumed (cynaobacterium as well) this is the endosymbiosis
Then ancestral eukaryote instead of breaking down consumed bacteria, it stays with the eukaryote and form chloroplast and mitochondria so are protected
The ancestral eukaryote and chloroplast and mitochondria live in —— and explain
Symbiosis where both benefit
Parasitises
One organisms deprives the other of nutrients “abuse”
Bacteria evolved into —— making
Mitochondria hence produce energy making human cells possible
Chloroplast and mitochondria features that looks like prokaryotes
Contain circular DNA
70S ribosomes
Double membrane - inner looks like bacteria outer looks like plant cells
Similar size to prokaryotes
Mitochondria description and function
Highly folded inner membrane called cristae
Enzymes for respiration in membrane
Watery region called matrix
ATP synthase in cristae (stalked particles)
Site of aerobic respiration providing energy in the form of ATP
How is mitochondria adapted for its function
Folded inner membrane called cristae creates large surface area for aerobic respiration to occur efficiently
Enzymes for respiration in membrane to speed up process without getting used up
Chloroplasts description and purpose
Stroma- watery region where second stage of photosynthesis occurs - the synthesis of sugars made from enzymes
Thylakoid membrane bridges gap between grana
Grana is stack of membrane
Stalked particles found in thylakoid membrane
Chloroplast envelope contains double membrane that is highly selective about movement into and out of organelle
Viruses are
Acellular hence no structure and neither prokaryotic or eukaryotic
MRS GREN for viruses do which of them
Reproduce
Sensitivity - attach to cell
Viral genetic material
Could be dna (2 strands) or found as rna (one strand)
Packaged in protein head called capsid
Virus structure
Nuclei acid surrounded by protein capsid a matrix and a lipid envelope with attachment proteins.
Viral replication
Virus attaches to host cell and injects Genetic material
GM used as code to synthesise more nuclei acids and proteins
New Viruse particles are assembles
Viruses burst out and destroy cell
Plant organs
Palisade myseophyll made out of palisade cells on leaf for photosynthesis
Spongy myseophyll for gasesous diffusion
Epidermis is protection and gas diffusion
Phloem transports sugars away from leaf
Xylem transports water to leaf
Danger of using chemo
Affect normal cell cycle
Why are large mammals made out of small cells
So there is enough SA to absorb nutrients and let go off waste quickly
Unicellular organism as large as elephant can not exist as the exact he of materials would not be quick enough
Cell surface membrane structure
Phospholipid bilateral with fatty acid tails facing each other. Cholestrol in plants. Fluid Mosaic. Protein carriers and channel. Glycolipids and glycoproteins
Bacterial DNA vs human DNA differences
Naked dna
Linear/plasmids
No histones vs histones
Binary fission vs mitosis
