Biochemistry 2 Flashcards
Which four elements do amino acids contain?
NOCH
Carbon, hydrogen, oxygen and nitrogen
From this, there are 20 different variations
What are amino acids made up of?
Every amino acid has a Carboxylate group/acid at one end and an amino group at the other… Hence amino acid
They also have an R group which is a sidechain that determines its characteristics
What is an amino acid and how many types are there in the body?
Amino acids of the building blocks for proteins.
The body needs 20 different amino acids to create the proteins needed to function.
What is the bond between two amino acids and between three amino acids called. Give examples of each.
A dipeptide is when two amino acids are joined together and an example is aspartame. This example does not occur in nature however and is manufactured.
It is also a neurotoxin.
Tripeptide is when three amino is joined together and an example is glutathione which is a powerful antioxidant.
Why are pH levels so important when it comes to amino acids?
The pH of the fluid the protein will affect its 3-D structure. If the pH level that the enzyme requires to work is not available, it will unravel and its shape will change. It will become denatured.
The shape of the protein works like a lock and key, and if they unravel they weren’t fit the lock and won’t function properly.
Describe what drives the 3-D structure of proteins
Nonpolar amino acids are hydrophobic and when a protein folds up in a water environment they like to be on the inside.
Conversely, polar amino acids are hydrophilic and they like to be on the outside of the protein structure in a water environment.
It is the combination of the polar and nonpolar amino acids that ultimately determine the 3-D shape of the protein
List at least five functions of proteins
- Structure of body tissues
- Movement.
- Carrying molecules for substances (haemoglobinh
- Storage molecules (ferritin)
- Fluid balance in the blood (Albumin)
- Enzymes
- Immune function
- Clotting Mechanisms
What is denaturation and how can it happen?
Proteins have unreeled and lost their shape and therefore no longer functional properly because they cannot fit their lock.
It can happen from
- heat - think about egg whites
- Heavy metals
- Wrong pH
Talk me through protein digestion
- Proteins mechanically broken down in the mouth to increase the surface area for enzymes to work on.
- Chemical digestion starts in the stomach where the enzyme pepsin breaks down protein chains.
(Pepin is released by gastric chief cells in the inactive form of pepsinogen. It is the presence of hydrochloric acid with pH of approximately 2 that converts pepsinogen into pepsin. - As protein in chyme enters the small intestine the hormone CCK is released which triggers the pancreas to release pancreatic juices.
- Pancreatic juices contain protein enzymes the continue to work on the polypeptide chain breaking it down to di and tripeptides.
- Enzymes in Villi brush border of the small intestine continue this work breaking tri and di peptides into single peptides in amino acids.
- Amino acids and small peptides are then absorbed into the blood.
What are the 2 most common nucleic acids and how are they different structurally?
They are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
RNA is a single strand of nucleotides which contain the sugar ribose.
DNA is a double-stranded structure and instead has the sugar deoxyribose.
It is a molecule of mRNA that copies specific subsections of DNA (genes) from DNA
What are nucleic acids?
They are the largest molecules in the body and they are used to store our genetic information.
DNA and RNA are the most common nucleic acids. Every living cell in the body contains at least one DNA molecule. They are huge and could be extracted to 2 m long.
What are the building blocks of nucleic acids?
Building blocks of nucleic acids are called nucleotides.
Nucleotides consist of
- a phosphate group
- Sugar
- nitrogenous base
There are four possible nucleotide bases in different patterns, giving us all the information we need to make all of our human proteins.
Adeline always pairs with thymine. Guanine always pairs with cytosine
How is the DNA recipe made available for a protein to produce?
- DNA is unzipped at the relevant section and the gene exposed?
- mRNA takes a copy of the recipe matching the bases of the DNA. TRANSCRIPTION
- mRNA leaves the nucleus of the cell and goes to ribosome where it is translated into a protein. Ribosomes are like the chefs that read the recipe to make a protein.
TRANSLATION - The protein chain will be released and fold up into its 3-D shape.
What is the end section of a chromosome called? What might affect their length?
They are called telomeres and they are ike the shoelaces tips at the end of DNA.
The shorten as cells and tissues age and this can be accelerated through things like stress, poor nutrition, poor sleep, chemical agents, a lack of exercise and even negative thoughts
What is a mutation?
A change in the sequence of amino acids in the protein which will likely change it 3-D shape and ultimately its function
What do you mean by gene expression?
We can’t change our genes but there are many different things that can change - our gene expression – which is whether we copy the gene and make the protein or not.
Our body is really flexible with this. An example might be someone who hasn’t drunk alcohol for six months and then goes out for a birthday celebration. The enzymes in their liver the breakdown alcohol have diminished because they haven’t been needed They will therefore be more affected by the alcohol but if they continue to drink over the next month more liver enzymes will be produced and tolerance for alcohol will get higher.
What affects gene expression?
There are many things that send signals to ourselves telling them whether or not to copy a particular gene. If we copy a gene we are making it. If we don’t copy it we are expressing less of it.
Gene expression is affected by:
- Acidic, anaerobic, toxic, stressful and glucose rich environments bathe our genes in a negative way and influence gene expression
- the metabolites vitamin A, vitamin D, essential fatty acids and zinc.
- Components of fibre can also have an effect on gene expression by affecting hormone levels and intestinal Flora
Give an example of how gene mutations can affect enzyme activity
MTHFR is an enzyme whose job it is to methylate folate. Methylation is used to control gene expressions and get rid of certain toxins like homocysteine and heavy metals. It is a very important process.
Some people have a genetic mutation in this enzyme which makes it about 50% efficient compared to a healthy version.
If they have this mutation then they will likely have a build up of homocysteine which is part of the methylation cycle and is involved in excess in diseases such as dementia and cardiovascular disease. When someone is methylating healthily homocysteine levels are low.
Someone with this mutation could have high homocysteine levels but if they are bathing themselves in the right nutrients, the environment it can compensate for the genetic difference.
Explain what is meant by an enzyme
Enzymes of biological catalysts made from protein the speed up reactions.
Enzymes are vital for life. They participate in every single chemical reaction in the body. Without them everything in our body would stop.
They are not themselves changed in the process so they can be used over and over again.
In enzyme reactions the molecules at the beginning of the process are called substrates and the enzyme converts them into a molecule known as a product..
The substrate sits in the enzyme active site which slightly stresses the chemical bond making it easier to break the bond or an enzyme allows two things to come closer together to make it easier to bond
How do enzymes work?
They are proteins that are folded into a very specific 3-D shape. It is this shape that is the key to how they work.
Each enzyme has an active site which has a unique shape that is complementary to the shape of the substrate molecule.
This is known as the lock and key.
Explain what is meant by an enzyme cofactor and give one example
Factor is a vitamin or mineral that the enzyme requires in order to function correctly.
A lack of cofactor can lead to a reduction in enzyme activity.
This is relevant for us because if we have a deficiency of a co-factor it will affect the enzymes reaction.
For example, zinc is required for the enzyme that breaks down alcohol – alcohol dehydrogenase.
Selenium is required for the antioxidant enzyme glutathione peroxidase. A lack of selenium compromises the livers ability to produce this.
What might affect enzyme function?
- If an enzyme is denatured and therefore not the right shape due to high temperature or conditions that are too acidic or too basic
- Enzymes co- factor is not available
- if there is too much substrate the enzyme can reach saturation point and cannot go any faster
List the digestive enzymes and where we find them
Mouth: salivary amylase to breakdown starch
Stomach:
- Pepsin working on protein in the stomach
- gastric lipase working on fats in the stomach
Small intestine: pancreatic enzymes.
- Pancreatic amylase works on the starches,
- pancreatic lipase works on the fat and
- pancreatic proteases work on proteins.
Small intestine:
brush enzymes - sucrase, Maltese and lactates do the final breakdown of disaccharides to allow transport into the blood.
What can influence a persons ability to produce digestive enzymes?
- Modern dietary habits overtax digestive enzymes when we eat large portions and when we eat continuously.
- There is too much substrate and not enough enzymes to efficiently convert that substrate into a digested form. The result is fermentation and putrification of food further down in the intestines.
- although enzymes are reusable, once they’ve gone into the intestinal track they will end up in the toilet and new ones and needed to be produced and digest the next meal. If we’re constantly snacking, we are constantly releasing enzymes into the digestive system and we don’t give our body enough time to build up enzyme supplies.
- Drinking whilst eating also interferes with enzyme function because it interferes with the correct pH in the stomach
- Prolonged stress turns off digestion
- Nutritional deficiencies meaning co factors are not available
What nutrients are needed and what stage in order for energy production to function correctly?
Glycolysis – Mg + B3
Acetyl coA formation - B1 + B3 + B5 + lipoic acid
Krebs cycle - Mg + Mn + Fe + B1+ B2+ B3
electron transport chain - FE + S + CU + CoQ10
Fill the gaps in this sentence
Match the enzyme with the food it is found in
??!?? What is the energy carrier NAD made with
FAD - B2
What nutrient is needed at what stage I. The electron transport change
What is coenzyme A synthesised from
B5
What is the name of the process that chops up fatty acids into acetyl CoA’s in the Kreb cycle?
Beta-oxidation
Match the protein function with the Protein structure
List at least five functions of proteins
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