cells and control Flashcards
chromosomes
coils of DNA
diploid
23 pairs of chromosomes / 46 total
haploid
23 chromosomes
Which body cells are haploid?
sex cells / gametes
Why are gametes haploid?
so that they can combine during fertilisation to form the diploid amount
cell cycle
a series of steps that a cell must undergo in order to divide
When does the cell cycle start?
when a cell has been produced by cell division
When does the cell cycle end?
with the cell dividing to produce two identical cells
What are the two stages of the cell cycle?
interphase and mitosis (and cytokinesis)
What two things happen during interphase and why is each thing happening?
- The chromosomes are being copied into two sister chromatids attached to each other at the centromere. This is so that each daughter cell is genetically identical to this parent cell. 2. The cell grows in size and creates more organelles so that once the daughter cells divide, they have enough organelles to survive.
Is the DNA visible as chromosomes with a light microscope during interphase?
No
mitosis
the stage in the cell cycle when the cell reproduces itself by splitting in two to form two genetically identical offspring
When does cytokinesis occur?
shortly before the end of telophase
What happens during cytokinesis?
The cytoplasm and cell membrane divide to produce two genetically identical diploid daughter cells, each with its own nucleus.
four stages of mitosis
prophase, metaphase, anaphase, telophase
What three things occur during prophase?
- The sister chromatids condense, becoming shorter and fatter. 2. The nuclear envelope breaks down to allow the sister chromatids to move around in the cell cytoplasm. 3. The centrioles begin to move to opposite poles of the cell.
What two things happen during metaphase?
- The sister chromatids line up at the cell’s equator. 2. The sister chromatids are moved by spindle fibres, which extend out from the centrioles and connect to the sister chromatids’ centromeres.
What two things happen during anaphase?
- The spindle fibres shorten, separating the sister chromatids at the centromere into daughter chromosomes. 2. These daughter chromosomes are pulled by the spindle fibres to opposite poles of the cell.
What happens during telophase?
New nuclear envelopes form around each group of daughter chromosomes, to form two daughter nuclei in the parent cell cytoplasm.
Which three things is mitosis important for?
growth, repair, and asexual reproduction
Why is mitosis important in growth?
so that an organism can grow to adult size by making more cells
Why is mitosis important in repair?
so that an organism can replace damaged cells by creating new cells
Why is mitosis important in asexual reproduction?
so that an organism can reproduce by generating genetically identical cells, or clones
Describe the division of a cell by mitosis.
the production of two daughter cells, each with identical sets of chromosomes in the nucleus to the parent cell, and that this results in the formation of two genetically identical diploid body cells
What is cancer caused by?
mutations in a cell’s DNA
What are tumours and how are they formed?
Some cells which lose control of their cell cycle keep dividing to produce masses of undifferentiated cells called tumours.
How do tumours cause cancer?
They spread and destroy organs
three treatments for cancer
surgery, chemotherapy, and radiotherapy
How can surgery be used to treat cancer?
by cutting out and removing the tumour if accessible
How can chemotherapy be used to treat cancer?
use drugs that are toxic to cells that keep dividing to kill tumours
How can radiotherapy be used to treat cancer?
use targeted beams of radiation to kill tumours
What are percentile charts used for and why?
To monitor the rate at which an organism of interest is growing, so that an overall pattern in development can be seen and any problems identified.
three measures to monitor the growth of babies
head circumference, mass, and length
A baby born at the 25th percentile for mass is […] or the […] as […]% of babies of the […].
A baby born at the 25th percentile for mass is heavier or the same weight as 25% of babies of the same sex.
two ways abnormal growth may be identified using percentile charts
- an increase or decrease of two or more percentile lines over time 2. an inconsistent pattern (a small baby with a large head
two examples of problems which can be identified from abnormal head circumference growth
microcephaly (too small) hydrocephalus (too large)
three examples of problems which can be identified from abnormal mass growth
childhood obesity (too fast) malnutrition (too slow) potential troubles with feeding or digestion (too slow)
two examples of problems which can be identified from abnormal length growth
- growth hormone issues 2. potential underlying health issues
two things growth in an organism may result in
an increase in size, or mass (or both)
two processes by which animal growth occurs
cell division, and cell differentiation
Cell division happens by […].
Cell division happens by mitosis.