Cell Division, Cell Diversity and Cell Differentiation, 2.6 Flashcards
What are the different stages of interphase?
G1 - growth. S - DNA copied. G2 - growth..
What does haploid mean?
One copy of chromosome
What does diploid mean?
Two copies of chromosomes
What is mitosis used in?
Asexual reproduction. Growth. Tissue repair.
What occurs during prophase?
- Chromosomes more distinct - coil, condense, thicken
- Centriole divides
- Nucleolus less prominent
- Nuclear envelope disintergrates
What occurs during metaphase?
- Each centriole at its pole
- Centrioles produce spindle fibres - attach to centromere
- Pairs of chromosomes pulled to the equator
What occurs during anaphase?
- Spindle fibres contract and centromere divides
2. Chromosomes pulled t opposite poles - in a v-shape
What occurs during telophase?
- Chromatids reach the poles - de condense
- Nuclear envelope reforms
- Cell contains two nuclei
What occurs during cytokinesis?
Cell divides. Animal - constriction, folds inward, ‘nips in’ cytoplasm. Plant - cell wall laid down.
What does mitosis produce?
Two identical daughter cells
What is the function of meiosis?
Sexual reproduction. Produces genetic variation. Haploid gametes eg work and egg..
How many divisions are there in meiosis?
Two
What occurs during Prophase 1?
- Chromatids condense and supercoil
- Nuclear envelope breaks down
- Crossing over occurs - non sister chromatids swap sections
What occurs during crossing over?
Non sister chromatids swap sections. Cut off at precise base pairs. No longer genetically identical.
What occurs during metaphase 1?
- Pairs of chromosomes line up on equator
2. Spindle attaches to centromere
What occurs during anaphase 1?
- Each one in the pair of chromosomes is pulled by the spindle to opposite poles.
- Centromeres do not divide
- Results in allele shuffling
What occurs during telophase 1?
- Nuclear envelope forms around each set of chromosomes
2. Chromosomes at poles
What does stage 2 of meiosis consist of?
Prophase 2. Metaphase . Anaphase 2. Telophase 2. The same as mitosis.
What does meiosis produce?
4 haploid cells.
How is genetic variation achieved?
Crossing over. Random distribution acts anaphase 1 and 2. Haploid gametes will fuse with another gamete.
What is differentiation?
Process by which stem cells become specialised into different types of cells.
What do zygotes divide by to develop?
Mitosis - it is a stem cell - become embryonic cells.
What are the key features of Erythrocytes?
Small and biconclave - large SA/V ratio. Flexible - can move through small capillaries. No nucleus - more space for haemoglobin.
What are the main features of neutrophils?
Invest invading pathogens. Large. Multilobed nucleus. Attracts to infected sites by chemotaxis. Phagocytosis.
What are the main features of spermatozoa?
Many mitochondria - lots of ATP. Small, long and thin. Enzymes released from across in head. Head contains male gamete nucleus.
What are the main features of epithelial cells?
Lining tissue. Squamous - flattened. Have cilia.
What are the main features of palisade cells?
Large. Packs tightly - leave air spaces for CO2. Large vacuole - pushes chloroplasts to the edge. Many chloroplasts.
What are the main features of guard cells?
Light energy - produces ATP - actively transports K+ ions - lowers water potential. Water enters via osmosis. When turgid open stomata.
What are the main features of root hair cells?
Hair like projection - increases SA - more can be absorbed. Mineral ions actively transported - lower water potential. Have carrier proteins.
Define tissue
A group of cells working together to perform a specific function.
What is epithelial tissue?
Covers surface of the body
What are the main features of epithelial tissue?
Cells packed tightly - form continuous sheets. No blood vessels - nutrients diffuse through tissue fluid. Have short cell cycles.
What are the functions of epithelial tissue?
Protection. Absorption. Filtration. Excretion. Secretion.
Name some examples of connective tissue..
Cartilage. Hyaline. Fibrous cartilage. Elastic.
What are the key features of cartilage?
Holds joints together. Cells are chondoplasts - divid by mitosis,secrete extracellular matrix.
What are the key features of hyaline?
Forms embryonic skeleton. Covers ends of long bones, joins ribs.
What are the key features of Fibrous Cartilage?
Discs between vertebrae in the spin and in the knee joint.
What are the key features of elastic cartilage?
Makes up outer ear.
Define an organ
Collection of tissues working together to perform the sam function
Define an organ system
Number of organs working together to carry out an overall life function
Give some examples of organ systems
Digestive system. Circulatory state.
Name 3 tissues found in Plants.
Epidermal. Vascular. Meristematic.
What are the key features of epidermal tissue?
Flattened cells. Covers leaves, stems and roots.
What are the key features of vascular tissue?
Contains stems cells. Found in roots and shoot tips. Thin walls. No chloroplasts. Small vacuole. Can divid
Name four plant organs and their functions.
- Leaf - photosynthesis.
- Root - anchorage, absorption, storage
- Stem - support, transportation systems
- Flower - sexual reproduction
What are stem cells?
Unspecialised cells able to express all of its genes and divide by mitosis.
What are the sources of stem cells?
Embryos. Umbilical cord blood. In developed tissues - adipose, blood, brain, bone, muscle, skin.
What are thee uses of stem cells?
- Bone marrow transplants - use to treat diseases of the blood and immune system
- Drug research - tests new drugs on lab stem cells
- Research of development history
What experiments have stem cells been used in?
Treat ice with type 1 diabetes. Develop liver cells. Develop into nerve tissue to treats Alzheimer’s.
