Module 2.1 cell structure ocr a level bio

    Cards (46)

    • What is the cell cycle?
      A regulated cycle of division with intermediate growth periods
    • What are the stages of the cell cycle?
      1. Interphase
      2. Mitosis or meiosis (nuclear division)
      3. Cytokinesis (cytoplasmic division)
    • What happens during interphase?
      Cell synthesizes proteins for replication, DNA replicates, and organelles divide
    • What occurs during the G1 phase of interphase?
      The cell synthesizes proteins for replication and doubles in size
    • What occurs during the S phase of interphase?
      DNA replicates, resulting in chromosomes consisting of two sister chromatids
    • What happens during the G2 phase of interphase?
      Organelles divide
    • What is the purpose of mitosis?
      To produce two genetically identical daughter cells for growth, cell replacement, and asexual reproduction
    • What are the stages of mitosis?
      1. Prophase
      2. Metaphase
      3. Anaphase
      4. Telophase
    • What happens during prophase?
      Chromosomes condense, centrioles move to opposite poles, and the nuclear envelope breaks down
    • What happens during metaphase?
      Sister chromatids line up at the cell equator, attached to the mitotic spindle by their centromeres
    • What happens during anaphase?
      Spindle fibres contract, centromeres divide, and sister chromatids are pulled to opposite poles
    • What happens during telophase?
      Chromosomes decondense, and new nuclear envelopes form around each set of chromosomes
    • What happens during cytokinesis?
      A cell membrane cleavage furrow forms, leading to the contractile division of the cytoplasm
    • How is the cell cycle regulated?
      Checkpoints regulated by cell-signalling proteins ensure damaged cells do not progress
    • What happens at each key checkpoint in the cell cycle?
      • Between G1 & S: Checks for DNA damage
      • Between G2 & M: Checks chromosome replication
      • Metaphase checkpoint: Checks that sister chromatids are attached to the spindle correctly
    • What is meiosis?
      A form of cell division that produces four genetically different haploid cells known as gametes
    • What happens during meiosis I?
      Homologous chromosomes pair to form bivalents, crossing over occurs, and the cell divides
    • What are homologous chromosomes?
      A pair of chromosomes with genes at the same locus, one maternal and one paternal
    • What happens during meiosis II?
      Independent segregation of sister chromatids occurs, producing four haploid cells
    • How does meiosis produce genetic variation?
      Through crossing over during meiosis I and independent assortment of chromosomes
    • How do cells become specialised?
      Some genes are expressed while others are silenced due to cell differentiation mediated by transcription factors
    • What is a transcription factor?
      A protein that controls the transcription of genes
    • How do transcription factors work?
      They move into the nucleus, bind to the promoter region, and affect RNA polymerase binding
    • What is a stem cell?
      Undifferentiated cells that can divide indefinitely and turn into other specific cell types
    • What are the four types of stem cells?
      • Totipotent: can develop into any cell type including the placenta and embryo
      • Pluripotent: can develop into any cell type excluding the placenta and embryo
      • Multipotent: can only develop into a few different types of cell
      • Unipotent: can only develop into one type of cell
    • What are some uses of stem cells?
      Repair of damaged tissue, drug testing, treating neurological diseases, and researching developmental biology
    • What can stem cells do indefinitely?
      Stem cells can divide indefinitely and turn into other specific cell types.
    • What are the four types of stem cells and their definitions?
      • Totipotent: can develop into any cell type including the placenta and embryo.
      • Pluripotent: can develop into any cell type excluding the placenta and embryo.
      • Multipotent: can only develop into a few different types of cell.
      • Unipotent: can only develop into one type of cell.
    • What are some uses of stem cells?
      • Repair of damaged tissue (e.g., cardiomyocytes after myocardial infarction).
      • Drug testing on artificially grown tissues.
      • Treating neurological diseases (e.g., Alzheimer’s & Parkinson’s).
      • Researching developmental biology (e.g., formation of organs, embryos).
    • What are the two groups of specialised cells in blood?
      • Erythrocytes (red blood cells): biconcave, no nucleus, lots of haemoglobin to carry oxygen.
      • Leucocytes (white blood cells): include lymphocytes, eosinophils, neutrophils to engulf foreign material, and monocytes.
    • How do specialised cells in blood form?
      Specialised cells in blood form from multipotent stem cells in the bone marrow.
    • What is the relationship between a system and specialised cells?
      • Specialised cells → tissues that perform specific functions → organs made of several tissue types → organ systems.
    • Describe the structure of simple squamous epithelium.
      • Single smooth layer of squamous cells.
      • Thin and flat with a round nucleus.
      • Fixed in place by a basement membrane.
    • Describe the structure of ciliated epithelium.
      • Made of ciliated epithelial cells.
      • Column-shaped with surface projections called cilia.
      • Cilia move in a synchronised pattern.
    • What is the specialised structure of a spermatozoon?
      A spermatozoon is specialised to fertilise an ovum during sexual reproduction in mammals.
    • Describe the structure and function of palisade cells in plants.
      • Specialised to absorb light energy for photosynthesis.
      • Contain many chloroplasts.
      • Pack closely together.
    • Describe the structure and function of guard cells in plants.
      • Form stoma.
      • When turgid, stoma opens; when flaccid, stoma closes.
      • Walls are thickened by spirals of cellulose.
    • Describe the structure and function of root hair cells.
      • Specialised to absorb water and low-concentration minerals from soil.
      • Hair-like projections increase surface area for osmosis.
      • Carrier proteins for active transport.
      • Many mitochondria produce ATP for active transport.
    • What are meristems in plants?
      Meristems are totipotent undifferentiated plant cells that can develop into various types of plant cells.
    • Describe the structure of a vascular bundle.
      • Phloem tissue.
      • Xylem tissue.
      • Cambium (meristematic tissue).