Biochemical Molecules Flashcards
Type of bonding for water?
Polar covalent bonding
What do polar and non polar molecules have?
Polar molecules have an unequal distribution of charge. Non polar molecules have equally distributed charge throughout its atoms)
In water what does the -ve oxygen molecule attract?
The +ve hydrogen atoms of other water molecules. This is called hydrogen bonding.
What is it that gives water is biological features?
The hydrogen bonds
Solvent features (water):
The tiny charges on the molecules attract other charged molecules or ions. These molecules spread around in between the water molecules- dissolving.
Excellent solvent due to its polar nature (examples are ions carried by plasma and urea in urine).
Viscosity and lubrication effect of water
Water has a low viscosity, important for the flow of blood. Yet its lubricating nature makes it useful in synovial fluid).
Why is water important for living organisms (4)
Water is a reactant in chemical reactions: hydrolysis reactions
Water is transport medium: transports glucose and oxygen
It’s a solvent, meaning substances can be dissolved in water and transported
Used in temperature control.
Temperature asserts (of water)
When heat energy is added to water, a lot of energy is used to break h bonds
Little energy is left to raise the temperature
Water needs a lot of energy to raise its temperature high specific heat capacity
Water needs a lot of energy to raise its temperature high specific heat capacity
Why is this important in the body?
Stops rapid temperature changes: temperature kept fairly constant
Water is Thermo-stable (high specific heat capacity) meaning that a lot of energy is required to break the hydrogen bonds between the molecules, thus keeping aquatic environments fairly steady despite external fluctuations in temperature.
Also a lot of energy is used to break H bonds for evaporation (high latent heat of evaporation)
How is this useful in the body?
Water in sweat on the skin surfaces absorbs heat energy from the body as it evaporates. Causing cooling.
What does the upthrust in water permit?
Enables aquatic animals to be much larger than terrestrial
Density features (water):
Solid water is less dense than liquid, means cold snap aquatic organisms can survive under the frozen surface (ice floats on water).
Transparent features (water):
Water is transparent, essential for photosynthesising aquatic plants and enables aquatic animals to see their food and/or predators
Cohesion and surface tension features (water):
Water molecules stick together due to its polarity.
Allows water to flow easily and transport substances.
Upper most molecules are pulled downwards as they have no water molecules above them.
Pulling force draws them closer together forming strong surface tension
The “sticky” nature of the water makes it a habitat for light invertebrates like pond skaters using the surface tension of water. This polar nature means that water can rise in xylem a considerable distance.
Stem cells
All cells begin as undifferentiated cells and originate from mitosis or meiosis. They’re not adapted to any particular function (unspecialised) and they have the potential to differentiate and become any one of the range of specialised cell types in the organism. Stem cells are able to undergo cell division again and again, and the source of new cells necessary for growth, development, and tissues repair.
What happens once a cell specialises
they lose ability to divide, entering the G0 phase of the cell cycle.
Describe and explain the activity and replication of stem cells
Activity of stem cells are strictly controlled, not divide fast enough, then tissues aren’t efficiently replaced leading to ageing. Uncontrolled division can form masses of cells called tumours, lead to development of cancer.
Potency
stem cell’s ability to differentiate into different cell types. Stem cells differ depending on the type of cell they can turn into.
Totipotent
differentiate into any type of cell (e,g is a fertilised egg, or zygote) they’re usually destined to provide a whole organism (can also differentiate into extra-embryonic tissues.
Pluripotent
can form all tissue types but not whole organisms
Multipotent
Can only form a range of cells within a certain type of tissue (haematopoetic stem cells in bone marrow are multipotent because this gives rise to various types of blood cells).
Differentiation
Why in multicellular organisms, do cells have to specialise?
to take on different roles in tissues and organs (adapted and so have different shapes and sizes and contain different organelles).
What happens when cells differentiate, and what forms this adaptation/ what’s it dependant on?
When cells differentiate they become adapted to their specific role. What forms this adaptation takes is dependent on the function of the tissue, organ and organ system to which the cell belongs.
What do cell require energy for? (ATP)
three main types of activity: synthesis (of large molecules like proteins), transport (pumping molecules or ions across cell membranes by active transport) and movement (of protein fibres in muscle cells that cause muscle contraction).
Inside cells, what molecules are able to supply energy
Adenosine triphosphate
ATP
What’s an ATP molecule composed off?
f a nitrogenous base, a pentose sugar and three phosphate groups. It is a nucleotide. The base is always adenine, and there are three phosphate groups. The sugar in ATP is ribose, as in RNA nucleotides.
What is ATP known as?
Universal energy currency
What happens when ATP is broken down?
A small amount of energy is needed to break the relatively weak bond holding the last phosphate group in ATP. However a large amount of energy is then released when the liberated phosphate undergoes other reactions involving bond formation. Overall a lot more energy is released than used.
As water is involved in the removal of phosphate group (another example of what sort of reaction?)
Hydrolysis reaction
Ethics on stem cells
Removal stems cells, destruction of embryo (although techniques being implemented to not damage it). Not only religious objections to the use of embryos, but moral ones too, many believe life begins at conception, so destruction of an embryo is murder. There is a lack of consensus as to when the embryo itself has rights, and also who owns the genetic material that is being used for research (controversy is holding back progress). The use of plant stem cells does not raise the same ethical issues as animal cells.
List some uses of stem cells
transplanted into specific areas have the potential to treat certain diseases such as: heart disease (muscle tissues damaged result of heart attack, normally irreparable), type 1 diabetes (body’s own immune system destroys the insulin producing cells in pancreas), Parkinson’s disease (symptoms of shaking and rigidity, caused by the death of dopamine-producing cells in the brain), Alzheimer’s disease (brain cells are destroyed as a result of the build up of abnormal proteins), macular degeneration (blindness in elderly and diabetics), birth defects, spinal injuries, treatment of burns, drug trials and developmental biology (study).
What are the sources of animal stem cells?
Embryonic stem cells- present at very early stage of embryo development and are totipotent. After 7 days a mass of cells (blastocyst) forms and the cells are now in a pluripotent state. Tissue (adult) stem cells- present throughout life from birth, found specific areas (bone marrow). They’re multipotent, although there’s growing evidence can be artificially triggered to become pluripotent. Stem cells can also be harvested from the umbilical cord of new borns, for future use for the individual (won’t be rejected).
Source of plant stem cells?
present in meristematic tissue (meristems). This tissue is found wherever growth is occurring in the plant (tips or roots and shoots). Also located sandwiched between phloem and xylem tissues (vascular cambium). These cells differentiate to the cells present in the phloem and xylem tissues. In this way the vascular tissues grows as the plant grows. The pluripotent nature of stem cells in meristems continues throughout the plants life.
Does hydrolysis of ATP happen in isolation?
does not happen in isolation, but in association with energy-requiring reactions. Reaction are said to be “coupled” as they happen simultaneously. ATP is hydrolysed into adenosine diphosphate (ADP)a and a phosphate ion, releasing energy.
What does the instability of the phosphate bonds in ATP mean?
that it is not a good long term energy source (fats and carbohydrates much better).
How is ATP created, from ADP
The energy released from the breakdown of fats and carbohydrates (through cellar respiration), used to create ATP, through reattaching a phosphate group to an ADP molecule (phosphorylation). As water is removed in the process, example of condensation reaction.
Why do/can’t cells store large amounts of ATP
Due to instability of ATP, cells don’t store large amounts. However ATP is rapidly reformed by the phosphorylation of ADP. Inter conversion of ATP and ADP is constantly happening in living cells, meaning cells do not need a large store of ATP.
Inter conversion of ATP and ADP is constantly happening in living cells, meaning cells do not need a large store of ATP, what does this allow?
Allows there to be a good immediate energy store
What does the structure and properties of ATP permit?
means that it is well suited to carry out its function in energy transfer.
Properties of ATP:
- Small, moves easily into and out of and within cells
- Water soluble, energy requiring processes happen in aqueous environments
- Contains bonds between phosphates with intermediate energy: large enough to be useful for cellular respiration but not so large that energy is wasted as heat.
- Releases energy in small quantities, quantities are suitable to most cellular needs, so that energy is not wasted as heat.
- Easily regenerated, can be recharged with energy.
