Flashcards in C1- Cell Biology Deck (42):
For what and how are red blood cells specialised?
Indentation: more surface area to absorb oxygen.
For what and how are plant cells specialised?
-Vacuole to hold sap
-Cell wall for rigid, stable structure.
-Cytoplasm contains mobile chloroplasts for photosynthesis.
For what and how are sperm cells specialised?
-Long tail and streamlined head to swim to the egg.
-Lots of mitochondria to provide energy.
-Enzymes in its head to digest through the egg cell membrane.
For what and how are nerve cells specialised?
-Long to cover more distance when carrying electrical signals.
-Branched connections to attach to other nerve cells and form a bodily network.
For what and how are muscle cells specialised?
-Long for space for contraction.
-Lots of mitochondria to generate energy for contraction.
For what and how are root hair cells specialised?
Absorbing minerals and water.
-Cells that grow into long hairs on the surface of plant roots; gives the plant a large surface area for absorbing water and mineral ions from the soil.
For what and how are phloem and xylem cells specialised?
Transporting substances in plants.
-Long cells that join end to end to form phloem/xylem tubes.
-Hollow so that the tubes can transport substances such as food and water.
-Few subcellular structures to make space for transporting substances.
Fancy word for egg and sperm/ sex cells?
State the stages of gametes to specialisation.
Gametes > fertilisation (egg becomes zygote) > cell divides, collection of stem cells made (embryo) > specialisation/differentiation (genes are turned off and different subcellular structures form) > forms foetus.
Why do cells specialise?
So that they can perform specific functions.
What are the two types of stem cells, where can they each be found and what is the difference?
Embryonic: can be found/taken from embryos that are a few days old, before the 8 cell stage. These have all the genes switched on so they can become any type of cell.
Adult/mature: can be found in the brain, heart and bone marrow. Because not all the genes are switched on, they cannot differentiate into any type of cell. For example, bone marrow stem cells can become red blood cells but not gametes.
What are mature stem cells used for?
Repairing or replacing cells.
What could embryonic stem cells be used for?
-Replacing/ repairing defunct cells in sick people, like brain cells for Parkinson's disease, nerve cells for paralysed people or insulin producing cells for diabetics.
-Cloning via removing embryonic stem cells and developing an embryo in the lab.
-Developing replacement organs/tissues to implant in people who need them.
What are adult stem cells used for?
Used to cure disease, e.g. transferring bone marrow stem cells from a healthy to a sick person.
Why are some people for/against stem cell research?
Some believe a potential human life is more valuable than experimentation. Some argue that the cells used are from unwanted embryos in fertility clinics so they may as well be used for progress in curing disease.
What are the pros and cons of using stem cells to cure disease?
-stops self consciousness
-brings an end to side effects from other treatments.
-can be very expensive
-long term effects unknown
-can only work in specific cases
-could lead to misuse
-stem cells could attack body cells because they think they're foreign
-not a fully developed technology
The process by which particles from an area of high concentration move down a concentration gradient to an area of lower concentration.
Of active transport and diffusion, which process is active and which is passive? What do the terms mean?
Active transport is active (requires energy from respiration). Diffusion is passive (doesn't require applied energy, uses the intrinsic energy of the random movement of particles).
Why doesn't diffusion happen in solids?
Not enough internal energy and molecules can't move.
What factors increase the rate of diffusion?
-Moisture (gases dissolve first so diffuse faster).
-Thinner membranes (easier for particles to get through).
-Temperature (more internal energy).
-Higher concentration gradient (more particles; quicker net movement).
The movement of water particles across a partially permeable membrane, from a region of higher water concentration to an area of water concentration.
The movement of water particles across a partially permeable membrane, from a dilute to a more concentrated region. (This is because it is the concentration of solute, not solvent).
What is the word for a plant cell that is full of water?
What is the word for a plant cell that is floppy and lacking in water?
What is the word for a high water/low solute concentration?
What is the word for a low water/high solute concentration?
Define active transport.
The process by which substances are absorbed against a concentration gradient.
Give two examples of active transport.
-Plant root hair cells absorbing water and minerals from the soil- the concentration of these is usually higher in the roots so diffusion cannot be used.
-Taking glucose from the gut- when there is a higher concentration of glucose and amino acids in the gut, they naturally diffuse into the blood. When it's the other way around, active transport is needed so that glucose can be transported to cells and used for respiration.
What happens in ribosomes?
Proteins are made.
What happens in the cytoplasm?
Most of the cell's reactions happen, which are controlled by enzymes.
What happens in the mitochondria?
Aerobic respiration reactions take place, providing energy to the cell.
Describe a chromosome. Where are they found?
Composed of strands of DNA coiled around proteins. Found in the nucleus.
How many chromosomes in a human body cell?
46 or 23 pairs.
What do chromosomes carry and what do these things do?
Genes, which control the development of different characteristics.
Why is there reference to 23 pairs of chromosomes rather than just 46?
Body cells have two copies of each chromosome, called a homologous pair (a maternal and paternal chromosome).
What does a homologous pair of chromosomes control and why?
One characteristic because the alleles on the arms of a chromosome (chromatids) are identical.
What is the word for the arm of a chromosome?
What does the cell cycle involve?
The production of new cells for growth, development and repair.
What are the two main stages of the cell cycle? Which takes up more time?
Growth and DNA replication, which takes longer, and mitosis.
What happens in growth and DNA replication?
-DNA is originally spread out in long strings.
-The cell grows and increases the number of subcellular structures.
-DNA is duplicated and forms X shaped chromosomes (with identical chromatids) so that there's a copy for each cell.
What happens in mitosis?
-Chromosomes line up at the centre of the cell.
-Cell fibres pull the chromatids to opposite ends.
-Membranes form around each set of chromosomes, forming two nuclei.
-Finally, the cytoplasm and cell membrane divide into two, forming two daughter cells.
What are the five substages of the cell cycle? Which means what?
DNA is originally spread out in long strings. The cell grows and increases the number of subcellular structures.
DNA is duplicated and forms X shaped chromosomes (with identical chromatids) so that there's a copy for each cell.
Chromosomes line up at the centre of the cell and cell fibres pull the chromatids to opposite ends.
Membranes form around each set of chromosomes, forming two nuclei.
Finally, the cytoplasm and cell membrane divide into two, forming two daughter cells.