cells Flashcards
Function of plasma membrane
Made of lipids and protein, Regulates the movement of substances in and out of the cell.
Function of the cell wall
A rigid structure that surrounds plant cells Support plant cells and is made of the carbohydrates cellulose
Function of the nucleus
Controls the cells activities by controlling the transcription of DNA which contains instructions to make proteins
Function of the nucleolus
Makes ribosomes
Function of chromatin
Contains coils of DNA bound to proteins (histones). During cell division chromatin condenses to form the chromosomes.
Function of the nuclear pores
Allow substances, e.g. RNA, to move between the nucleus and the cytoplasm to the ribosome for protein synthesis
Function of lysosomes
Around organelle surround by membrane Contains digestive enzymes and can digest invading cells or breakdown worn out components of the cell
How does the endosymbiosis theory (eukaryotes engulfed the prokaryotes but couldn’t digest them) explains why chloroplast and mitochondria (organelles in eukaryotes) have their own DNA?
- Reproduction process (from existing cells) is similar to the one of bacteria (which is a prokaryote)
- Similar sizes to bacteria
- They all have their own protein synthesising machinery like bacteria which means They have their own ribosomes like bacteria (70s)
- The genome resembles that of bacteria not the nucleus genome
- it has circular DNA
- it has double membrane
Function of Ribosome
- Made of protein and rRNA
- Floats or is attached to RER
- The site where proteins are made
rough endoplasmic reticulum
RER
- An extensive network of flattened sac like membranes surrounding fluid (cisternae)
- extends from the nuclear membrane into the cytoplasm,
- Folds and processes proteins that have been made at the ribosomes surrounding
Function of the smooth endoplasmic reticulum SER
- Syntheses and processes lipids
- Found in eukaryotic cells
Vesicles
A small fluid filled sac in a membrane, Transport substances in and out of the cell and between organelles
Function of Golgi apparatus
Group of fluid filled membrane bound flattened sacs (cisternae), packages new lipids and proteins to produce secretary vesicles. It’s also makes lysosomes
Function of Mitochondrion
Rod shaped with a double membrane called Cristae and lamella (inner folded membrane to increase surface area where respiratory processes take place) and the matrix. Is The site of aerobic respiration so they generate atp (not produce)
Function of Chloroplast
Found in plant cells
Contains the grana membrane made of lipids and tightly packed pigment-proteins which catalyse photosynthesis
Function of centrioles
- Self replicating Small hollow cylinders made of 9 bundles of microtubules,
- Found in animal cells
- Involved in the separation of chromosomes during cell division and Assembly of spindle fibres
Function of Cilia
Small hair like structures Found on the cell membrane of animal cells, Allow substances to move along the cell surface
Function of eukaryotic flagellum
Found in animal cells, 9 pairs + 2 Microtubules contract to make flagella move flagella are used like motors to propel cells forward
What are the Membrane bound organelles
RER
Mitochondria
Golgi apparatus
Lysosomes
Vacuole
Vesicle
Non-membrane bound
Ribosomes
Cytoskeleton
Centrioles
Function of membranes within the cell
- They separate areas from the rest of the cytoplasm to maintain the specific conditions in each organelle different to cytoplasm
- Provide a large surface area for attachments of enzymes for metabolic processes
- Allow ATP synthesis in mitochondria and photosynthesis in chloroplast to take place on the membrane
- Provide a transport system within the cell
Why does the cell have many mitochondria?
A cell with many mitochondria must be very active to need a lot of ATP
Why is the cells plasma membrane folded into microvilli
It must be absorbing a lot of material to need increased surface area
Why would a cell have a lot of RER?
It must be synthesising a lot of proteins
A cell has a lot of mitochondria and microvilli (indents on cell surface to increase SA) What does this indicate?
It must be absorbing a lot of material by active transport which requires a lot of ATP
Cytoskeleton function
- Is present in all eukaryotic cells
- Holds organelles in place and controls movement of organelles through the skeleton eg vesicles
- Contains microfilaments - contractile fibres made of actin responsible for cell movement and cell contraction during cytokinesis
- Contains microtubules - made of the protein tubulin and form scaffold structures that determine cell shape and acts as tracks for movement of organelles. They also form spindle fibres to move chromatids during mitosis and meiosis.
- maintains shape strength stability of cells
Production of insulin
- mRNA copy of the instructions (gene) for insulin is made in the nucleus
- mRNA leaves the nucleus through a nuclear pore
- Attaches to a ribosome which reads the instructions to assemble the protein (insulin)
- Insulin molecules are taken off in vesicles and travel towards the Golgi apparatus
- Vesicle fuses with Golgi apparatus
- Golgi apparatus processes and packages insulin molecules ready for release
- Packaged insulin molecules are taken off in vesicles from Golgi apparatus and moved towards cell surface membrane
- Vesicle fuses with cell surface membrane
- Cell surface membrane open to release insulin molecules outside
Production of protein
- The instructions to make the protein are in the DNA in the nucleus.
- The specific instruction to make the protein is known as the gene which is on a chromosome.
- The nucleus copies the instructions in the DNA into a molecule called mRNA.
- The mRNA leaves the nucleus through a nuclear pore and attaches to a ribosome possibly on the RER
- The ribosome reads the instructions and uses the code to assemble amino acids.
- The amino acid is folded into protein in the RER
- The protein is pinched off in a transport vesicle and transported to the Golgi which packs the protein and may modify it so it’s ready for release.
- then the protein is packaged into a secretory vesicle and fuses into the cell surface membrane where it’s secreted.
Gram Positive bacteria
Cell wall is a thick layer of murine
Stains purple
Gram negative bacteria
Thin layer of murine
Stains, red or pink
Prokaryote versus eukaryote: how/where is it found
Prokaryote: single celled
Eukaryote: found in a tissue
Prokaryote versus eukaryote: Nucleus
Prokaryote: no nucleus only chromosomal DNA in cytoplasm
Eukaryote : membrane bound nucleus
Prokaryote versus eukaryote: organelles
Prokaryote: no membrane bound organelles
Eukaryote: membrane bound organelles
Prokaryote versus eukaryote: respiration
Prokaryote: occurs in mesosome
Eukaryote: occurs in mitochondria
Prokaryote versus eukaryote: DNA
Prokaryote: naked DNA
eukaryote: DNA bound to histones to form chromosomes
Prokaryote versus eukaryote: cell wall
Prokaryote: peptidoglycan aka murine
Eukaryote : cellulose cell wall in plants
Chitin in fungi
Prokaryote versus eukaryote: flagella or cilia
Prokaryotes: Some have flagella
Eukaryotes : some have flagella or Cilia
Prokaryote versus eukaryote: ribosome size
prokaryote: 70s
Eukaryote: 80s
Prokaryote versus eukaryote: cytoskeleton
Prokaryote : no complex skeleton
eukaryote: has skeleton
Prokaryote versus eukaryote: average size
Prokaryote: 0.5um-2um
eukaryote: 20-40um
State the word that describes a structure made up of different types of tissue working together to perform a particular function
Organ
Why would a ciliated (needs mobility) cell need many mitochondria
To provide energy for aerobic respiration to move
Sperm cell
Head contains half the amount of chromosomes 23 in nucleus
Acrosome contains enzymes to digest outer portion of egg
Mitochondria releases energy for flagellum movement
Thin cell walls do not provide much support for a leaf so how is it supported?
Air spaces give buoyancy and is supported by water
Which component of the cytoskeleton provides tensile strength for the cell?
Intermediate filaments
True or false microtubules are part of the 9+2 formation in bacterial flagella
False only in eukaryotic
True or false microtubules can be prevented from functioning by respiratory inhibitor
True
True or false microtubules are involved in moving chromosomes from the equator to the poles of the cell during mitosis
True
Dynein proteins are responsible for causing microtubules to bend. a mutation gene causes them to be no longer expressed. suggest explain how this may lead to male infertility
Microtubules are responsible for the movement of the flagellum that moves the sperm cell carrying the DNA. The mutation would result in the flagellum no longer moving so the sperm cell will be unable to reach the egg and deliver genetic material.
Why is the nucleus of two eukaryotic cells the same weight?
Each cell would only contain one nucleus containing the same number of genetic material
Why would cytoskeleton degradation lead to a lack of control?
It may cause cells to lose strength/stability causing them to break down preventing vesicles from being transported through the cell to sell surface to secrete their contents
What is the cause of abnormal function of mitochondria?
Cells may not receive enough energy causing them to die which prevents them from carrying out their normal function
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.
Function of a temporary vacuole
- found temporarily in animal cells
- store or transport substances
Name this organelle (it looks like a vacuole)
Temporary/permanent vacuole
Function of a pili
- Are found in bacteria
- exchange DNA to other bacteria
- are hooks to anchor inside
Why do cells with more mitochondria grow faster
They would be able to respire aerobically which produces more ATP which releases more energy which is needed for processes like active transport, cell division, protein synthesis, DNA replication,
Therefore ATP allows faster metabolic processes, & meets high metabolic demand
How do you genetic codes code for specific proteins?
- The three bases code for one amino acid
- The sequence of bases determine the structure of the protein
How do vesicles move?
Attached to the cytoskeleton moved by protein motors called dynien same as in flagellum
Prokaryotes flagella
Made of the protein flagellin
Arranged in a helix
What is the difference between a tissue and an organ
Tissue is made of the same type of cell organs are made of different types of tissue
Function of mesosomes
- found in prokaryotic cells
- Coming off the inside of the cell membrane
- used for respiration like mitochondria
What is a chromosome?
46 in each human cell and carry information required to make a molecule, e.g. protein
Why might abnormal mitochondria be problematic in heart tissue
Not enough atp produced so heart might not have enough energy to contract
What is the advantages of two stains being used
Allow specific parts of the cell to be seen
how to differentiate a prokaryotic cell from a eukaryotic cell
Smaller cells, smaller Ribosomes, no nucleus, fewer organelles, no mitochondria, dna is circular not linear
How can you tell a cell undertakes active transport on a large scale
They have more mitochondria than usual to provide the energy needed to go against the concentration gradient
