Cell Structure Flashcards
How do cilia and flagella move
By the cytoskeleton protein that runs through them. So single cells with flagella the cytoskeleton propels the whole cell
Function of Golgi apparatus
It receives proteins from the rough er and modified them. It then packages the modified proteins into vesicles that can be transported. Some modified proteins may go to the surface of the cell so that they may be secreted.
What are lysosomes and what is the function of them?
Spherical sacs surrounded by a single membranes and they’re specialised vesicles.
They contain powerful digestive enzymes and they break down waste materials (inc old organelles). They also play an important role in breaking down pathogens.
Where is the cytoskeleton and what is the function of it?
Present throughout the cytoplasm of all eukaryotic cells.Organelles are held in place by cytoskeleton and can control movement of organelles through the skeleton.
What are the functions of micro filaments and micro tubules?
They are made of the contractile fibres made of actin and responsible for cell movement and also cell contraction during cytokinesis. Microtubules are made of tubulin and they form scaffold structures that determine the shape of the cells. They act as tracks for the movement of organelles.
What are centrioles and what’s the function of them?
Self replicating organelles made of nine bundles of microtubules and found mostly in eukaryotic cells. 2 centrioles form a centrosome(involved in the making of spindles fibres during cell division). They help in organising cell division but aren’t always needed in the process.Found in all animal some plant
Are animal cells and plant cells prokaryotic or eukaryotic
Eukaryotic
Describe and say the function of plasma membrane
Membrane found on surface of animal cells and inside cell wall of plant cells and prokaryotic it’s made of lipids and protein.
It regulates the moment of substances into and out of the cell.It also has receptor molecules which allow it to respond to chemicals like hormones.
Describe and explain function of cell wall
A rigid structure that surrounds plant cells and it’s mainly made of cellulose.
It supports plant cells
Describe and explain function of nucleus
A large organelle surrounded by a nuclear envelope(double membrane) which contains many pores. It contains chromatin(made from dna and proteins) and it has nucleolus.
It controls the cells activities (through transcription of dna).Pores allow substances to move between nucleus and cytoplasm.nucleolus makes ribosomes.
Describe and explain the function of ribosome
A very small organelle that either floats free in the cytoplasm or is attached to the rough ER. It’s made of proteins and RNA.not surrounded by membrane
Site where proteins made
Describe and explain function of RER
A system of membranes enclosing a fluid filled space. Surface is converted w ribosomes.
It synthesises and processes lipids
Describe and explain function of vessicle
A small fluid filled sac in cytoplasm surrounded by a membrane.
Transports substances in and out of the cell(via plasma membrane) and between organelle. Some formed in the golgi or ER which others formed at cell surface
Describe and explain function of mitochondrion
Oval shaped with a double membrane-inner one folded to form structures called cristae.Inside is Matrix, which contains enzymes involved in respiration.
It’s site of aerobic respiration where atp produced. Mitochondria found in large numbers in cells that at very active and require a lot of energy
Describe and explain function of chloroplast
A small flattened structure in plant cells. Surrounded by double membrane and has membranes inside called thylakoid membranes.these membranes stacked up in some parts of the chloroplast to form grana. Grana linked together by lamellae- thin flat pieces of thylakoid membrane
Where photosynthesis takes place, some pasty of this process happens in grana others happen in stoma
Describe and explain function of cilia
Small hair like structures found on surface membrane of animals cells. In cross section they have an outer membrane and a ring of nine pairs of protein microtubules inside with a single pair of micro tubules in the middle
The microtubules allow cilia to move . This moment is used by the cell to move substances along cell surface
Describe and explain function of flagellum
They stick out from cell surface and surrounded by plasma membrane. Inside they have two microtubules in the centre and nine pairs around the edge.
Microtubules contract the make the flagellum move.
Flagella are used like outboard motors to propel cells forward.
What are the differences between prokaryotic and eukaryotic
•Prokaryotic have extremely small cells where eukaryotic have larger
•Prokaryotic dna is circular eukaryotic dna is linear
•Prokaryotic no nucleus eukaryotic nucleus present. dna inside nucleus
•Prokaryotic cell made of polysaccharide and not cellulose or chitin eukaryotic there’s no cell wall(animals) cellulose cell wall(plant) or chitin cell wall (fungi)
•Prokaryotic few organelles and no membrane bound organelles. Eukaryotic many membrane bound organelles.
•Prokaryotic flagella made of flagellin arranged in helix.eukaryotic ich flagella made of microtubules arranged in a 9+2 formation.
Prokaryotic have small ribosomes eukaryotic have larger ribosomes
Examples of prokaryotic is e coli and salmonella
Eukaryotic is human liver cell yeast and aemoba.
Where are proteins made and describe the diff types of places proteins are made
At the ribosomes. Ribosomes on RER make proteins that are excreted or attached to the cell membrane. Free ribosomes in cytoplasm make proteins that stay in cytoplasm
How does protein production work?
polypeptide chains synthesised on the RER
polypeptide chains then moved to the cisternae in RER and packaged into vesicles
secretory vesicles carry the portions to the cell surface membrane where it fuses and releases the membrane via exocytosis
What is the cytoskeleton
A network of protein threads
What are the proteins threads arranged as in eukaryotic cells
Microfilaments and microtubules.
What are the functions of the cytoskeleton?
•Microtubules and microfilaments support the cells organelles keeping them in position
•They also help to strengthen the cell and maintain its shape
•They’re also responsible for transport of organelles and materials within the cell.
•Proteins of the cytoskeleton cause cell to move
How does chromosomes seperate during cell division
Due to contraction of microtubules in the spindle
How do vessicles move
Attached to the cytoskeleton and moved by protein motors called dymein same as in flagellum
Function of a permanent vacuole
are found in plant cells
• is a fluid-filled sac membrane that stores water and nutrients on which a cell can rely for its survival
Filled with cell sap to help keep the cell turgid
maintains pressure by pushing the cytoplasm against the cell wall, which helps keep the plant cell turgid and prevents plants from wilting.
Why is the cells plasma membrane folded into microvilli
To increase SA for absorpption
Why would ciliary cells need many mitochondria
To make more atp for ciliary movement
Prokaryotes vs eukaryotes
Prokaryotes:
Small cells and unicellular
No membrane bound organelles and no nucleus
Circular dna not assosicated wih proteins
Small risbosomes 70s
Binary fission always asexual production
Made of murein (peotidoglycan)
Capsule sometimes
Eukaryotes:
Larger cells and often multicellular
Always have organelles and nucleus
Linear chromosomes associated with histones
Larger ribosomes (80s)
Mitosis and meiosis- sexual and/or asexual
Absent In animal cells,cellulose cell wall(plants),chitin (fungi)
No capsule,no plasmids,always cytoskeleton
Production of protein
1)instructions to make protein are in dna in nucleus
2) specific instruction to make the protein is the gene which is found on the chromosome
3)nucleus copies the instructions in dna into molecule called MRNA
4) mRNA molecule leaves the nucleus though a nuclear pore and attached to a ribose in. Ribosome attached to RER
5) ribosome reads the instructions and uses codes to assemble the hormone(protein)
6)The assembled protein inside RER is pinched off in a vesicle and transported to golgi .
7) Golgi packages protein and may also modify it so it’s ready for release. Its packed into a vesicle and moves to the cell surface membrane,where its secreted outside
Whats the endosymbiosis’ theory
Both mitochondria and chloroplasts can only arise from preexisting mitochondria and chloroplasts. So they were prokaryotes ingested by another prokaryote
It can’t be made in a cell that lacks them bc DNA in nucleus encodes only some of the proteins which are made.
Would happened through endocytosis for one organism to have of engulfed the other
Evidence for endosymbiosis theory
Both mitochondria and chloroplasts have their own genome and it resembles the bacteria genome and not nuclear genome.
Chloroplasts have circular dna not double stranded,bacteria has circular which is another link
Mitochondria have smaller ribosomes found in other prokaryotes suggesting that they too were one free living prokaryotes.eukaryotes usually have bigger ribosomes
Similar size to bacteria- shows they were once free living bacteria
Function of mesosomes
Inward folds in the membrane of bacteria which are used for respiration
What’s gram positive bacteria
Cell wall made of thick layer of peptidoglycan/murine
And inner plasma membrane
stains purple
Gran negative bacteria
Thin layer of peptidogylcan/murine-
Stains red/pink
Cause of abnormal function of mitochondria
Cells may not recieve enough energy causing them to die
Cause of abnormal function of mitochondria
Cells may not recieve enough energy causing them to die
Why is nuclear weight of two eukaryotes the same
Contains same amount of genetic content eg chromosomes
