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Biology paper 2 - Coggle Diagram
Biology paper 2
protein synthesis
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The order of the bases on the DNA tells us the order for combining amino acids to create particular proteins.
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template used - The template is used to guide protein synthesis on ribosomes located in the cytoplasm.
delivery of amino acids - Specific amino acids are delivered by carrier molecules to the protein chain, where they are added in the order shown on the template.
unique structure created - Once complete, the long protein chain folds up, giving it a unique structure.
This unique structure is essential to the protein’s function, in the form of enzymes, hormones, or structural proteins (e.g. collagen).
endocrine systems
The endocrine system coordinates the body’s response to changes in the environment using chemical messengers (hormones). Hormones are released by glands into the bloodstream, where they travel to target organs. There are lots of different endocrine glands
Pituitary gland
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It is found in the brain and is linked to the hypothalamus (part of the brain that receives signals from receptors).
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adrenal gland
The two adrenal glands are situated above each kidney.
They produce adrenaline, which triggers the ‘fight or flight’ response when an organism is presented with a dangerous situation
pancreas
The pancreas produces insulin and glucagon, both of which are involved in regulating blood glucose levels
ovaries (female only)
The ovaries produce oestrogen, which controls puberty and is one of the main hormones in the regulation of the menstrual cycle
thyroid gland
This gland is in our neck and releases thyroxine.
Thyroxine regulates our metabolism, heart rate and temperature
testes (male only)
The testes produce testosterone, which controls puberty and sperm production
food chains
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Food chains nearly always begin with a producer that makes its own food. This is usually a green plant or algae that can photosynthesise.
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the genome
The genome is the entire (all) genetic material of an organism. Within a genome, there are lots of levels of organisation
A gene is a small section of DNA. Genes code for a sequence of amino acids, which combine to give a specific protein.
DNA is a double helix polymer, which means it is a polymer (a large molecule made up of many subunits) made up of two strands forming a twisted, ladder shape
chromosomes
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Human body cells contain 23 pairs of chromosomes, one of each pair coming from each parent.
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homeostasis
Homeostasis describes all of the processes that happen in a cell or organism to maintain (keep) optimal conditions. This is needed to respond to changes in the internal and external environment
Because humans are organisms that live in a changing environment, we must regulate our body’s internal conditions to make sure our enzymes and cells function well.
If conditions are not optimal, then our enzymes can denature (change shape).
This reduces their ability to catalyse (speed-up) metabolic reactions (chemical reactions in organisms)
Humans must regulate their body’s internal conditions to make sure that enzymes and cells function well. The conditions that need to be regulated are:
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reproduction
cell division
meiosis
This results in the formation of four genetically non-identical daughter cells.
Meiosis is used in sexual reproduction
mitosis
This results in the formation of two genetically identical daughter cells.
Mitosis is used in asexual reproduction
sexual reproduction
The process of reproduction where the nuclei of two gametes (sex cells) fuse to form a zygote (a process known as fertilisation), producing offspring that are genetically different to one another. There are four key features of sexual reproduction
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asexual reproduction
Asexual reproduction is the process of reproduction that forms genetically identical offspring from only one parent. Asexual reproduction is common in single-celled organisms and some plants. There are four key features of asexual reproduction:
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DNA
DNA is a polymer made up of two long strands of small units that repeat throughout the structure, called nucleotides. Each of these is made up of a sugar, a phosphate and a base attached to the sugar
structure
The two long strands within each DNA molecule are held together by attractions between opposite bases.
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nucleotides are made up of a sugar, a phosphate and a base attached to the sugar
genotypes
If the two alleles are different, we say that the person is heterozygous (Bb).
If the two alleles are the same, we say that the person is homozygous (BB or bb).
punnet squares
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Punnett squares are diagrams that help us to visualise the outcome of a monohybrid cross. In these diagrams, a capital letter shows a dominant allele.
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hormones
thyroxine
Thyroxine is the main hormone secreted (released) by the thyroid gland. It increases the basal (resting) metabolic rate
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regulation
Production is regulated by a negative feedback loop. This allows the body to maintain a fairly constant concentration of thyroxine in the blood.
When the concentration of thyroid hormones, such as thyroxine, in the blood is low, the production of thyroid-stimulating hormone (TSH) is increased. This stimulates the secretion of thyroxine by the thyroid gland.
When the concentration of thyroid hormones in the blood is high, TSH production is decreased.
adrenaline
Adrenaline increases heart rate and blood pressure, and dilates the pupils in our eyes
In times of fear or stress, adrenaline is part of the so-called ‘fight or flight’ response, preparing the body to move and think quickly in response to danger
Adrenaline enlarges the air passages of the lungs and alters metabolism in order to boost the delivery of oxygen and glucose to the brain and the muscles
plant hormones
Plants produce hormones that allow them to respond to changes in the external environment. The key plant hormones are:
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auxins
Auxins change growth patterns to allow roots and shoots to move either towards or away from a stimulus (change in conditions).
Responses to stimuli that involve directional growth are called tropisms
tropisms
phototropism
These involve growth either towards (positively phototropic) or away from (negatively phototropic) a light source.
auxin distribution
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This unequal auxin distribution will result in increased cell elongation (grows longer) on the shaded side.
In shoots, auxins promote the elongation of cells.
However, in roots, auxins prevent the elongation of cells.
geotropism/gravitropism
Growth either towards (positively gravitropic) or away from (negatively geotropic) the direction of gravity
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