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
A round membrane bound sac Containing digestive enzymes that 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 made of phospholipid bilayer called cisternae surrounding fluid
- membrane extends from the nuclear membrane into the cytoplasm,
- Covered with ribosomes on the outside
- 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
- had double membrane; Cristae (inner folded membrane) to increase surface area where respiratory processes take place
- has the matrix: (like the cytoplasm) site of aerobic respiration to generate/release ATP (not produce)
- intermembrane space is the outside of the cristae Separating it from the matrix
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
- Contains microfilaments - contractile fibres made of actin responsible for cell movement of cilia and flagella and cell contraction during cytokinesis
- Contains microtubules - made of the protein tubulin and form scaffold structures that determine cell shape, maintains shape/stability of cells, hold organelles in place and acts as tracks for movement of organelles and vesicles during exocytosis and endocytosis.
- microtubules also form spindle fibres to separate chromatids during mitosis and meiosis.
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 agene 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.
- 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 by exocytosis
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 circular 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 cytoskeleton
Prokaryote versus eukaryote: average size
Prokaryote: 0.5um-2um
eukaryote: 20-40um similar to blood cells
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
Microtubules
- are part of the 9+2 formation in eukaryotic flagella allowing sperm movement
- microtubules can be prevented from functioning by respiratory inhibitor
- microtubules are involved in moving chromosomes from the equator to the poles of the cell during mitosis
Dynein proteins are responsible for causing microtubules to bend. a mutation gene causes them to be no longer expressed. 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 flagella 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 to respire often enough causing them to die out which prevents them from respiring
Function of a permanent vacuole
- are found in plant cells
- is a fluid-filled sac membrane that stores water and nutrients which a cell relies on for 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
- hair like structures found on the surface of prokaryotes especially bacteria
- exchange DNA to other bacteria
- are like hooks to anchor on to other bacteria
Why do cells with more mitochondria grow faster
Cells respire more aerobically - provides more ATP - releases more energy - needed for processes like cell division, protein synthesis, DNA replication used for growth
Therefore more ATP allows faster metabolic processes, & meets high metabolic demand
How do genetic codes code for specific proteins?
- three non overlapping bases code for one amino acid
- The sequence of bases determine the sequence of amino acids which determines the primary structure of the protein
How are proteins transported out of the cell from ribosomes on RER after translation
- Transport vesicles are formed from RER to Golgi apparatus
- modification/processing/folding occurs of the protein
- then are packaged back into secretary vesicle
- this moves along the cytoskeleton propelled by diynein motors.
- The vesicle fuses with cell surface membrane
- Secretion occurs by exocytosis
Explain how vesicles move
They attach to the cytoskeleton and are propelled by protein motors called dynein
what are Prokaryotes flagella made of
the protein flagellin
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?
they carry information required to make a molecule, e.g. protein
there are 46 in each human cell
Why might abnormal mitochondria be problematic in heart tissue
Not enough atp produced so heart might not have enough energy to contract
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 uses active transport on a large scale
They have more mitochondria than usual to provide the energy needed to go against the concentration gradient
