Cells and Control Flashcards
what does the nucleus contain?
genetic material in form of chromosomes
define diploid
two copies of each chromosome (46)
define haploid
half the number of chromosomes (23)
what’s a cell cycle?
lifecycle of a cell involving cell growth, DNA replication and cell division
describe the stages of mitosis.
- interphase : sub cellular structures increase in size, DNA is replicated (forms X shape) and energy stores are increased
- PROPHASE : chromosomes condense and membrane around nucleus break down
- METAPHASE : chromosomes line up in the middle of the spindle fibers
- ANAPHASE : cell fibres pulled apart of each arm of the DNA goes to the opposite sides of the cell
- TELOPHASE : membranes form around each set of chromosomes to become nuclei
- CYTOKINESIS : cytoplasm and cell membrane divide to form two identical daughter cells
why is mitosis important in organisms?
- asexual reproduction
- growth
- repair of damaged cells
- cell replacement
what does mitosis produce?
- two genetically identical diploid daughter cells
- used for somatic cells
- identical set of chromosomes as parents
what’s mitotic index?
how many cells are involved in mitosis (prophase - telophase )
a cell divides by mitosis every 2 minutes. calculate the number of identical cells present after 10 minutes.
10/2 =5
2^5 = 32 cells
define growth
increase in size/mass
describe growth in animals.
- when young, cells divide at a fast rate. animals reach the full growth and stop and cell division is only required to repair/replace damaged cells.
- most cells differentiate in early stages and become specialized. specialized cells can produce more through mitosis. some adult stem cells retain ability to differentiate
describe growth in plants
- cell division occurs in the meristem and rate stays the same as long as the plant lives
- cell elongation occurs in all cells as they expand and enable growth of plant
- meristem stem cells can differentiate into any cell type for as long as the plant lives
what is cancer?
- a change in genes controlling cell division has a change which results in uncontrollable cell division
- mass abnormal cells forms primary tumor
- as tumor invades and destroys other surroundings it forms secondary tumors - what we call cancer
what are percentile charts?
chart used to assess baby’s growth overtime
- measures mass, length and head circumference
what can a doctor determine from percentile charts?
- slower growth than normal (below the bottom line)
- faster growth than normal (above top line)
- abnormal growth (irregular growth patterns)
what does the 50th percentile mean?
baby is bigger than 50% of babies
what are stem cells?
undifferentiated cell which can undergo cell division and later differentiate
why is cell differentiation important?
enables formation of specialised tissues with specific functions
explain what are embryonic stem cells
form when egg and sperm cell fuse to produce zygote
- can differentiate into any kind of cell
- can clone these and direct into any part of body ( used for replacing insulin producing cells for diabetics)