Eukaryotes & Prokaryotes

• 𝙁𝙀𝘼𝙏𝙐𝙍𝙀𝙎 𝙊𝙁 𝘼𝙉 𝘼𝙉𝙄𝙈𝘼𝙇 𝘾𝙀𝙇𝙇:

  • nucleus and nucleolus
  • mitochondria
  • smooth endoplasmic reticulum
  • rough endoplasmic reticulum
  • centriole
  • Golgi apparatus/body
  • vesicles
  • ribosomes
  • cell membrane
• 𝙁𝙀𝘼𝙏𝙐𝙍𝙀𝙎 𝙊𝙁 𝘼 𝙋𝙇𝘼𝙉𝙏 𝘾𝙀𝙇𝙇:

  • nucleus and nucleolus
  • central vacuole
  • Golgi apparatus/body
  • cytoskeleton
  • plasmodesmata
  • peroxisome
  • cytoplasm
  • mitochondria
  • cell membrane
  • cell wall made of cellulose
  • chloroplast
  • smooth endoplasmic reticulum
  • rough endoplasmic reticulum
  • ribosomes
• The cytoskeleton is a network of protein filaments in the cytoplasm. It provides structure and organisation, resists and transmits stresses, and drives shape change and movement.
• Peroxisomes are small vesicles that contain digestive enzymes for breaking down toxic materials.
• 𝙁𝙀𝘼𝙏𝙐𝙍𝙀𝙎 𝙊𝙁 𝘼 𝘽𝘼𝘾𝙏𝙀𝙍𝙄𝘼𝙇 𝘾𝙀𝙇𝙇:

  • circular DNA
  • plasmids
  • cytoplasm
  • ribosomes
  • cell membrane
  • cell wall made of murein
  • slime capsule
  • pili
  • flagella
• 𝗧𝗛𝗘 𝗡𝗨𝗖𝗟𝗘𝗨𝗦:

  The nucleus is the membrane-bound central control centre of the eukaryotic cell and manages the cell's genetic material. The nucleus contains the cell's DNA, organised into chromosomes, and is responsible for controlling the cell's growth and division.

  The nuclear envelope helps to maintain the shape of the nucleus. It is connected to the endoplasmic reticulum so that the internal chamber of the nuclear envelope is continuous with the lumen (inside) of the ER. This also allows the transfer of materials.

  It is found in both animal and plant cells.

  
• 𝗧𝗛𝗘 𝗠𝗜𝗧𝗢𝗖𝗛𝗢𝗡𝗗𝗥𝗜𝗔:

  The primary function of the mitochondria is to produce energy (ATP) through aerobic cellular respiration. This process converts the energy stored in food into a form that can be used by the cell and is essential for the survival and growth of the cell.

  Mitochondria have a double membrane structure, with an inner layer with many folds to create a high surface area. This provides more space for more metabolising proteins and therefore they are able to create more energy at one time.

  They are found in both plant and animal cells.

  
• 𝗧𝗛𝗘 𝗖𝗛𝗟𝗢𝗥𝗢𝗣𝗟𝗔𝗦𝗧:

  The chloroplast synthesises food by the process of photosynthesis. It absorbs light energy and converts it into chemical energy. Chloroplast has a structure called chlorophyll which functions by trapping solar energy and is used for the synthesis of food in all green plants.

  The chlorophyll is the site where light-dependent photosynthesis takes place. The presence of a large number of tiny holes in the epidermis, called stomata, helps in the diffusion of carbon dioxide and oxygen into and out of the leaves (respectively).

  Found in plant cells.

  
• Photosynthesis takes in the chloroplasts of plant cells. Chloroplasts contain fluid-filled sacs called thylakoids. Thylakoids are stacked up like pancakes to form structures which we call grana. Each granum is connected together by pieces of thylakoid membrane called lamellae. The gel-like substance which surrounds the thylakoids is called the stroma.

  
• 𝗧𝗛𝗘 𝗘𝗡𝗗𝗢𝗣𝗟𝗔𝗦𝗠𝗜𝗖 𝗥𝗘𝗧𝗜𝗖𝗨𝗟𝗨𝗠:

  Rough: its main function is to produce proteins in the cells and ribosomes are attached to its surface.

  Smooth: its main function is to produce lipids and detoxify toxins in the body in the liver and kidney cells.

  The proximity of the rough ER to the cell nucleus gives the ER unique control over protein processing. The rough ER is able to rapidly send signals to the nucleus when problems in protein synthesis and folding occur and thereby influences the overall rate of protein translation.

  It is found in both plant and animal cells.

  
• 𝗧𝗛𝗘 𝗚𝗢𝗟𝗚𝗜 𝗔𝗣𝗣𝗔𝗥𝗔𝗧𝗨𝗦:

  A cellular organelle involved in the processing, packaging, and distribution of molecules within or outside of the cell. Its structure consists of a series of flattened membrane-bound sacs, called cisternae, organised into stacks with each one having a distinct polarity (a cis face where molecules enter, and a trans face where molecules exit).

  It functions as a factory in which proteins received from the ER are processed and sorted for transport to their eventual destinations (lysosomes, secretion, etc).

  It is found in both plant and animal cells.

  
• Resistance towards an antibiotic is gained by a mutation in a bacterium's alleles. This can occur due to overuse of an antibiotic or failure to complete a full course of one. The resistant bacteria survive and reproduce, and the resistance allele becomes more frequent in the bacteria population. This is a problem in hospitals as more antibiotics are used here and patients have weakened immune systems.
• The nucleus is roughly spherical, double-membraned, and contains chromatin. It stores the cell's genetic information and produces t/m/rRNA, which codes for polypeptides. Material is able to move into and out of the nucleus through the nuclear pores in its membrane.
• Plant cell walls are made of the polymer cellulose.
• Fungal cell walls are made of the polymer chitin.
• Bacterial cell walls contain peptidoglycan.
• Explain how the use of antibiotics has led to antibiotic-resistant strains of bacteria becoming a common cause of infection acquired when in hospital.

  • ill people in hospitals use antibiotics frequently
  • some bacteria have antibiotic-resistant alleles
  • non-resistant bacteria die from antibiotics
• Describe the structure and function of the nucleus.

  STRUCTURE:

  • histones
  • contains the cell’s genetic material
  • contains a nucleolus
  • double membrane with pores

  FUNCTION:

  • where DNA replication occurs;
  • where protein transcription takes place;
• Describe how bacteria divide.

  1. Binary fission;
  2. Replication of circular DNA;
  3. Division of cytoplasm to produce 2 daughter cells;
  4. Each with single copy of circular DNA;
• Some proteases are secreted as extracellular enzymes by bacteria. Suggest one advantage to a bacterium of secreting an extracellular protease in its natural environment. Explain your answer.

  1. To digest protein;
  2. So they can absorb amino acids for growth;
  3. Or so they can destroy a toxic substance/protein;
• Scientists investigated treatment of a human bladder infection caused by a species of bacterium. This species of bacterium is often resistant to the antibiotics currently used for treatment. They investigated the use of a new antibiotic to treat the bladder infection. The new antibiotic inhibits the bacterial ATP synthase enzyme.

  What reaction is catalysed by ATP synthase?

  ADP + Pi --> ATP + H2O
• DNA and RNA can be found in bacteria. Give two ways in which the nucleotides in DNA are different from the nucleotides in RNA.

  • DNA contains thymine and RNA contains uracil;
  • DNA contains deoxyribose and RNA contains ribose;
• U. marinum cells ingest bacteria and digest them in the cytoplasm. Describe the role of one named organelle in digesting these bacteria.

  • lysosomes;
  • fuse with phagosome;
  • release hydrolytic enzymes;
• Give two structures found in all prokaryotic cells and in all eukaryotic cells.

  • ribosomes;
  • DNA;
• Suggest one explanation for the faster rate of plasmid replication in cells growing in a culture with a high amino acid concentration.

  • amino acids are used in protein synthesis;
  • so more enzymes are made for use in DNA replication;
• Give one feature of the chloroplast that allows proteins to be synthesised inside the chloroplast and describe one difference between this feature in the chloroplast and similar features in the rest of the cell.

  • ribosomes;
  • which are smaller than cytoplasmic ribosomes;
• Contrast the structure of the two cells visible in the electron micrographs shown in the figure above.

  • magnification figures show A is bigger than B;
  • A has a nucleus whereas B has free DNA;
  • A has mitochondria whereas B does not;
  • A has a Golgi body/endoplasmic reticulum whereas B does not;
  • A has no cell wall whereas B has a murein cell wall;
  • A has no capsule whereas B has a capsule;
  • A has linear DNA whereas B has circular DNA;
  • A has larger ribosomes;

  
• Eukaryotic cells produce and release proteins.

  Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells.

  Do not include details of transcription and translation in your answer.

  • DNA in the nucleus codes for proteins;
  • ribosomes/rough endoplasmic reticulum produce proteins;
  • mitochondria produce ATP for protein synthesis;
  • the Golgi apparatus packages/modifies;
  • vesicles transport;
• Name an organelle found in both a chloroplast and a prokaryotic cell

  • ribosomes;
• Name the structures labelled W to Z in the diagram.

  • W = cell surface membrane
  • X = cell wall
  • Y = capsule
  • Z = flagellum

  
• Name the main biological molecule in:

  • W = phospholipid
  • X = murein

  
• Name the process by which prokaryotic cells divide.

  • binary fission;
• Name the organelles labelled:

  • B = Golgi body
  • C = mitochondria

  
• Name two structures present in plant cells that are not present in animal cells.

  • chloroplasts;
  • vacuoles;
• Name the parts of the chloroplast labelled A and B.

  • A = stroma
  • B = granum

  
• Name two structures in a eukaryotic cell that cannot be identified using an optical microscope.

  • ribosomes;
  • endoplasmic reticulum;
• Give the name and function of the structures labelled W and Z.

  • W = chloroplasts - site of photosynthesis;
  • Z = nucleus - stores genetic information;