cells Flashcards
What is the basic structure of a plasma membrane?
It consists of a phospholipid bilayer with embedded proteins, allowing selective transport of substances.
What is the main function of the nucleus?
The nucleus contains genetic material (DNA) and controls the cell’s activities, including replication and transcription.
What are mitochondria responsible for?
Mitochondria are the site of aerobic respiration and ATP production.
Where does photosynthesis occur in plant cells?
Photosynthesis occurs in chloroplasts, specifically in the thylakoids for light-dependent reactions and the stroma for light-independent reactions.
What are ribosomes responsible for?
Ribosomes are the site of protein synthesis, translating mRNA into polypeptides.
What is the difference between rough and smooth endoplasmic reticulum?
Rough ER is covered with ribosomes and synthesizes proteins, while smooth ER synthesizes lipids and steroids.
What is the function of the Golgi apparatus?
The Golgi apparatus modifies, packages, and transports proteins and lipids from the ER into vesicles.
What do lysosomes do?
Lysosomes contain digestive enzymes that break down waste materials and cellular debris.
What is the role of the cell wall in plant cells?
The cell wall provides structural support and prevents the cell from bursting under osmotic pressure.
What is the function of the vacuole in plant cells?
The vacuole stores nutrients and waste products and helps maintain turgor pressure.
What is binary fission?
Binary fission is the process by which prokaryotic cells divide to form two genetically identical daughter cells.
How is mitosis different from meiosis?
Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically varied haploid cells.
What is the purpose of mitosis?
Mitosis is for growth, tissue repair, and asexual reproduction in eukaryotic cells.
What are homologous chromosomes?
Homologous chromosomes are pairs of chromosomes, one inherited from each parent, with the same genes but possibly different alleles.
Describe the structure of the phospholipid bilayer.
It has hydrophilic phosphate heads facing outward and hydrophobic fatty acid tails facing inward, forming a barrier to water-soluble substances.
What is the role of channel proteins in the membrane?
Channel proteins facilitate the transport of charged or polar molecules across the cell membrane.
What is facilitated diffusion?
Facilitated diffusion is the passive movement of molecules across the membrane via specific carrier or channel proteins.
How does active transport differ from passive transport?
Active transport requires energy (ATP) to move molecules against a concentration gradient, while passive transport moves molecules down a concentration gradient without energy.
What is osmosis?
Osmosis is the diffusion of water molecules across a partially permeable membrane from a region of higher water potential to lower water potential.
What are the steps of cell fractionation?
- Homogenisation of cells, 2. Filtration to remove debris, 3. Ultracentrifugation to separate organelles based on density.
What is the mitotic index?
The mitotic index is the ratio of cells undergoing mitosis to the total number of cells in a sample.
What is the importance of cholesterol in membranes?
Cholesterol regulates membrane fluidity, making it more stable and less permeable to very small molecules.
How do temperature and ethanol affect membrane permeability?
Higher temperatures and ethanol increase membrane fluidity, disrupting the phospholipid bilayer and increasing permeability.
What is co-transport?
Co-transport involves the coupled transport of two molecules across the membrane via a carrier protein, one moving down its concentration gradient driving the movement of another against its gradient.