UNIT 2: (2.1) Producing New Cells Flashcards
Mulitcellular organisms
what is a chromosome complement?
the definite number of chromosomes in each species of plants and animals
how many chromosomes are in most humans cells?
46
how many pairs of chromosomes are in most human cells?
2
what is meant by diploid?
any cell that contains two sets of matching chromosomes (2n)
what cells only contain one set of chromosomes?
gametes (sex cells)
what is meant by haploid?
any cell that contains only one set of chromosomes (n)
how many chromosomes are in gametes?
23
what are examples of haploid animal cells?
- sperm cell
- egg cell
what are examples of haploid plant cells?
- pollen grain
- ovule
what are examples of diploid animal cells?
- cheek cell
- nerve cell
- heart cell
what are examples of diploid plant cells?
- root hair cell
what is the importance of mitosis?
- mitosis provides new cells for growth and repair of damaged cells
- mitosis maintains the diploid chromosome complement
- in single-celled organisms, mitosis provides a means of reproduction
what is mitosis?
-takes place in diploid cells.
-when the nucleus divides into 2 daughter nuclei each of which receives exactly the same number of chromosomes that were present in the original nucleus.
maintains the full chromosome complement.
what is stage one in the process of mitosis?
chromosomes shorten, thicken and become visible as each chromosome makes a duplicate copy of itself ( chromosomes are now made up of pairs of chromatids)
Nuclear membrane begins to disintegrate and spindle fibres appear
what is stage 2 in the process of mitosis?
chromosomes now line up at the equator of the cell attached to the spindle fibres
what is stage 3 in the process of mitosis?
the spindle fibres contract, separating the pairs of chromatids
chromosomes now move to opposite ends ( poles) of the cell
what is stage 4 in the process of mitosis?
a nuclear membrane forms around each group of chromosomes and the cytoplasm divides
two new daughter cells are formed with a chromosome complement identical to the parent cell
how many chromosomes do cells contain at the start and end of mitosis?
4
were do all cells in the body originate from?
stem cells
what are stem cells?
unspecialized cells which can divide in order to self-renew. they have the potential to become different types of cell
what are stem cells involved in?
growth and repair
what sources do stem cells come from?
- embryos (embryonic stem cells)
- certain adult tissues (tissue stem cells)
were do embryotic stem cells come from?
- 4 or 5 day old human embryos
where do tissue stem cells come from?
- brain
- bone marrow
- blood
- blood vessels
- skeletal muscles
- skin
- liver
what is the function of the sperm cell?
to fertilize the egg
what are the specialised structures of a sperm cell?
- tail for movement to swim to the egg
- many mitochondria to provide energy to swim
what is the function of the red blood cells?
specialized to transport oxygen efficiently in the form of oxyhemoglobin
what are the specialized structures of red blood cells?
- biconcave in shape to increase the surface area to allow more oxygen to be absorbed
- haemoglobin which binds to oxygen
- no nucleus so more space for haemoglobin
what is the function of the neuron?
specialized to carry messages as electrical impulses around the body
what are the speacialed structures of a neuron?
- many connections at the end allowing one nerve cell to reach other nerve cells
- very long to carry information from one part of the body to another
what are examples of specialized animal cells?
- sperm cell
- red blood cells
- neurons
what are examples of specialised plant cells?
- root hair cell
- palisade cell
what is the function of a root hair cell?
specialised for absorbing water and dissolved minerals
what are the specialised structures of a root hair cell?
- long root hair attached to the root cell increases the surface area helps absorption of water and minerals
- thin cell wall easier for minerals to pass across
what is the function of the palisade cell?
specialised for photosynthesis
what are the specialised structures of palisade cell?
- lots of chloroplasts which have chlorophyll which absorbs light energy
- near-surface, column-shaped and closely packed together for continuous layer for absorption of sunlight
what does specialisation of cells lead to?
variety of cells, tissues and organs
what is the hierarchy of organisation?
cells —-> tissues —–> organs —–> systems
what is a tissue?
a group of specialised cells that have a similar structure and function
what is an organ?
groups of different tissues working together to perform a particular function
what is a system?
a group of organs which work together to perform a particular function
what is an example of a system?
circulatory system were the heart and blood vessels work together to transport substances around the body
what do multicellular have?
more than one cell type and are made up of tissues and organs
