Cells And Control Flashcards
What are chromosomes?
Coiled up lengths of DNA molecules found in the nucleus
What is a diploid cell?
Cell with two copies of each chromosome
What kind of cells undergo the cell cycle?
Body cells in multicellular organisms
What’s mitosis?
The stage of cell cycle when the cell divides. Organisms use mitosis to grow or replace damaged cells or to asexually reproduce
What happens in interphase?
DNA is spread out in long strings, cell growing to increase number of sub-cellular structures. DNA duplicates and forms x shaped chromosomes with identical left and right arms
Describe the events of Mitosis and Cytokenisis
Mitosis:
1; prophase: chromosomes condense, lie free in cytoplasm as membrane around nucleus breaks down
2; metaphase: chromosomes form a line at centre of cell
3; anaphase: cell fibres pull chromosomes apart, each arm of each chromosome go to opposite ends of cell
4; telophase: membranes form around each of the sets of chromosomes (these become nuclei of new cells)
cytokinesis; before telophase ends cytoplasm and cell membrane divide to form two separate cells
What does mitosis produce?
Two genetically identical diploid cells
What’s the equation to calculate number of cells after multiple divisions of a cell by mitosis?
Number of cells = 2^number of divisions by mitosis
What is growth?
An increase in size or mass
What’s cell differentiation?
Cell changes to become specialised, allowing multicellular organisms to work more efficiently
How is cell division done?
By mitosis
How do plants grow?
By cell elongation. Plant cells expand, so plant grows. Cell division happens in tips of roots and shoots. Plants grow continuously and continue to differentiate to develop new parts
How do animals grow?
By cell division. In most animals cell differentiation is lost at an early age and cell division for growth stops when animal reaches full growth
Hows cancer caused?
Gene controlling cell division mutates, cells divide uncontrollably, tumour is caused
What do growth percentile charts do? How do they work?
Assess a child’s growth over time, show an overall pattern of development. Three main measurements taken are length, mass and head circumference
The chart shows number of percentiles eg 50th percentile means the mass 50% of babies would’ve reached at a certain age
Doctors are likely to investigate if babies size are above top of below bottom percentile line, size increases/ decreases by 2 or more percentiles or there’s an inconsistent pattern
What are stem cells?
Unspecialised/ undifferentiated cells