Cell Division Flashcards
Mitosis- what happens in metaphase?
Chromosomes move to equator. Centromeres attach to spindles.
Mitosis- what happens in anaphase.
Centromeres break
Spindles shorten pulling chromatids towards poles.
Mitosis- what happens in telephase?
Chromosomes unravel
Nuclear envelope reforms.
Difference in meiosis
Crossing over of non- sister chromatids
Independent assortment
Random segregation
Mitosis- what happens in prophase?
Chromosomes condense and become visible to avoid tangeling. Centrioles move to opposite poles.
Nuclear membrane breaks down
What is differentiation in basic terms?
The process of stem cells becoming specialised into different types of cell
What are stem cells?
Undifferentiated cells
Where are epithelial cells found?
Lining cells- inside and outside of your body.
Eg- lining of your interesting and makes up the walls of alveoli and capillaries
What are characteristics of epithelial cells?
Squamous epithelial cells are flattered
Normally have cilia
Adaptations of sperm cell?
Many mitochondria
Small long and thin
Enzymes released from acrosome- specialised lysosomes
Contains haploid male gametes and little cytoplasm
Function of neutrophils
Attracted to and traced to sites of infection by chemotaxis
Ingest bacteria and fungi by phagocytosis
Adaptations of Erythrocytes
Very small- 7.5um diameter Large surface area to volume ration Biconcave shape Developed cytoskeleton- allows to twist and turn Are flexible
Function of erythrocytes?
Carries oxygen from lungs to respiring tissues
Travels through narrow capillaries
Oxygen can easily diffuse through their membrane and reach all regions inside the cell
Steps of differentiation
The proportion of organelles change
The shape of the cell changes
Some of the contents of the cell changes
Describe epidermal tissue (4)
Flattened cells
Lack chloroplasts (excluding guard cells)
Protective covering over leaves stems and roots
Some have walls impreganated with a waxy substance forming a cuticle
Function of vascular tissue? & examples
Transport
Xylem and phloem
What does meristematic tissue contain?
Stem cells
Where is meristematic tissue found?
Tips of shoots and roots
And in the cambium of vascular bundles
What is the area where stem cells are found?
Meristems
Describe the cells in meristems (4)
Thin walls containing little cellulose
Do not have chloroplasts
Do not have a large vacuole
Can divide by mitosis and differentiate
What do plant cells develop as they mature? & why?
Large vacuole
Rigid cell wall
To prevent cell from dividing
Where do new cells arise?
Meristems
What can cambium cells differentiate into?
Xylem vessels or Phloem sieve tuber or companion cells
Describe how cambium cells differentiate into xylem vessels?
Lignin is deposited in the cell wall
This kills the cells
The ends of the cells break down to form continuous columns with wide lumens
Describe how cambium cells differentiate into phloem sieve tubes
Sieve tubes loose most of their organelles
Sieve plates develop between them
Describe how cambium cells differentiate into companion cells?
Companion cells retain their organelles and continue metabolic functions to provide ATP
What is parenchyma?
Packing tissue
Fills spaces between other tissue
What does parenchyma do in 1) roots 2) leaves?
Store starch
Contains chloroplasts to photosynthesise (chlorenchyma)