M2 CH6: Cells Flashcards
Outline what happens during G1 phase of the cell cycle. (3)
- cell contents (except chromosomes) are duplicated.
- proteins synthesised
- CHECKP: chromosomes checked for damage
Outline the purpose of G0 phase of the cell cycle and what cells are found here. (3)
- cells with damaged DNA
- apoptosis
- e.g. neurones
Outline what happens during S phase of the cell cycle. (3)
- DNA is replicated
- chromosomes duplicated
- chromosomes become chromatids
- CHECKP: chromosmes checked that they have been replicated correctly.
Outline what happens during G2 phase of the cell cycle. (3)
- cell continues to grow
- energy stores increase
- CHECKP: DNA damage
State the reasons for mitosis. (4)
- growth
- repair
- production of stem cells
- asexual reproduction
outline what happens during prophase (mitosis). (3)
- chromosomes condense
- nuclear envelope and membrane breaks down
- spindle fibres attatch to centromeres
outline what happens during metaphase (mitosis). (2)
- spindle fibres pull the chromosomes to the centre of the cell.
- chromosomes line up along centre of the cell on the metaphase plate
outline what happens during anaphase (mitosis). (2)
- centromeres divide
- chromatids separated and pulled to opposite poles by the spindle fibres
outline what happens during telophase (mitosis). (2)
- chromatids reach the poles and uncoil
- nuclear envelope reforms around new sets of chromosomes
outline the difference between mitosis and meiosis. (2)
mitosis: 2 genetically identical daughter cells produced
meiosis: 4 genetically different daughter cells produced
outline how the meiosis stages differ to mitosis (4)
- prophase 1: crossing over, results in genetic variation
- metaphase 1: independent assortment of chromosomes (occurs in metaphase 2 also) along the metaphase plate.
- anaphase 1: chromosomes dont separate, DNA switched in prophase 1 is fused
- telophase 1: chromosome number is reduced from diploid to haploid
explain how cytokinesis differs between plants and animal cells. (3)
- animal cells: cleavage furrow forms around the middle of the cell. the cell surface membrane is pulled inwards by the cytoskeleton.
- plant cells: vesicles fuse in the centre and divide the membrane in half
state and explain how erythrocytes (RBCs) are adapted to their function. (3)
- flattened biconcave shape: increases their surface area: volume ratio
- no nuclei: more space to combine with oxygen and transport it around the body.
- flexible: able to squeeze through narrow capillaries.
state and explain how neutrophils (cells) are adapted to their function. (2)
- multi lobed nucleus: can squeeze through small gaps to get to infection sites.
-granular cytoplasm contains many lysosomes: contain enzymes that attack pathogens.
state and explain how sperm cells are adapted to their function. (2)
- flagellum containing many mitochondria: enables movement, mitochondria provides energy the sperm needs to swim
- acrosome contains digestive enzyme: breakdown the protective layers around the ovum, allows the sperm to penetrate the cell and fertilise
state where squamous epithelium tissue is found and explain how it is adapted to its function. (2)
- forms lung lining
- one cell thick: allows for rapid diffusion of oxygen into the blood
state and explain how ciliated epithelium tissue is adapted to its function. (2)
- cilia hair structures: move in rhythmic motion, promotes sweeping of substances e.g. mucus
- goblet cells: secrete mucus which traps particles, prevents them reaching lungs/alveoli (reduces risk as particles may be bacteria)
state and explain how cartilage tissue is adapted to its function. (3)
- contains elastin and collagen fibres
- chondrocyte cells embedded in extracellular matrix.
- prevents the ends of bones rubbing together and causing damage
state and explain how muscle tissue is adapted to its function.
- myosin and actin: sliding filament model, enables contraction of muscle
- skeletal muscle: contains microfibrils which contain contractile proteins, skeletal muscle pump
state and explain how palisade cells are adapted to their function. (4)
- chloroplasts: enables a lot of light to be absorbed for photosynthesis.
- square/box shaped: can be closely packed together to form continuous layer
- thin cell walls: increases rate of diffusion of carbon dioxide
- large vacuole: maintain the turgor pressure
state and explain how root hair cells are adapted to their function. (2)
- root “hairs”: increases surface area of cell, maximises water and mineral uptake
- thin cellulose cell wall: easy osmosis
state and explain how guard cells are adapted to their function (2)
- pairs on leaf cells: open and closing mechanism
when the plant loses too much water, they become less swollen, change shape and closes stomata to prevent any more water loss
state and explain how xylem tissue are adapted to their function (2)
- long hollow tubes of dead cells,
- lignin in walls: strengthens walls and provides structural support
state and explain how phloem tissue are adapted to their function. (3)
- columns of sieve tube cells
- perforated walls: sieve plates
- helps with transport of assimilates to where they are needed
explain what the term ‘potency’ means with regards to cells.
a cells ability to differentiate into different types of cells.
explain the term totipotent and give an example of a cell. (2)
capable of differentiating into any cell type or a complete embryo.
e.g. zygote
explain the term pluripotent and give an example of a cell. (2)
capable of differentiating into any tissue type but not a whole organism.
e.g. early embryos
explain the term multipotent and give an example of a cell. (2)
capable of differentiating into a limited range of cell types.
e.g. haematopoietic stem cells in bone marrow
state the sources of stem cells and what type of cell they are. (3)
embryonic: totipotent
adult: pluripotent
meristems: pluripotent
state some uses of stem cells
- type 1 diabetes
- heart disease
- parkinson’s
- spinal injuries
explain what the hayflick limit is.
the number of times a cell will divide before cell division stops. does not apply to stem cells.
