The Building Blocks Of Cells Flashcards
What is cell membrane
The outside of a cell (for animals) or the bit between the cell wall and the rest of the cell (plants) and controls what enters and leaves the cell
What is cytoplasm
The area in a cell in which chemical reactions take place. Also contains all the organelles
What is the job of the nucleus
An organelle with the DNA and controls the activities of the cell
What is mitochondria for
The organelle in which respiration occurs
What parts of a cell do plants and animals have in common
Cell membrane
Cytoplasm
Nucleus
Mitochondria
What is the cell wall
The outside of a plant cell made of cellulose and is used to support the cell and keep its shape
What is a vacuole
In a plant it is a large space in the cytoplasm that is filled with cell sap and helps support the shape
What are chloroplasts
Organelle in plants that contain chlorophyll, a green substance used for photosynthesis
What are bacteria
Single cell organisms with no nucleus
What are the parts and jobs of a bacteria cell
Chromosomal DNA with most of the important information. Large loop
Plasmid DNA with extra stuff. Smaller loops
Flagella to move the cell (not in all bacteria)
Cell membrane to control what goes in and out
Cell wall to keep the shape but isn’t made of cellulose like plants
What are chromosomes
They contain the genetic information and are in the cells nuclei. Chromosomes are made of DNA
What is DNA
DNA are the molecules that make chromosomes. They are in a double helix and are joined together by bases which pair with each other with weak hydrogen bonds. A section of DNA is called a gene
What is a gene
A section of DNA that contain instruction for specific proteins used in our body.
What are the base pairs and what do they do
Guanine cytosine
Adenine and thymine
They join the strands in DNA helix and the order of them contains the information needed to form proteins for out cells.
Why do bases always pair the same way
They are complementary shaped molecules (matching)
Who helped discover the shape of DNA and what was their role
Maurice Wilkins and Rosalind franklin took X-rays of purified DNA. This produce patterns and they could work out how atoms in the DNA were arranged
Francis crick and James Watson were trying to build a model. Maurice showed them the pictures and the detail in the pictures helped James and Francis build their model.
What was the HGP and what did it find out
HGP was the human genome project and consisted of scientists from 18 countries around the world sharing there discoveries on human genes. After 13 years, it was complete and the sequence of the 3billions base pairs that make a human genome was complete. It should that every human shares at least 99.9% of DNA
What are the benefits of knowing the human genome sequence
Easier to test for genetic disorders, find out if people have faulty alleles
Ew ways of finding genes that may increase the fish of certain diseases such as Alzheimer’s
New treatments and cures for disorders such as gene therapy where scientists try to replace or mend faulty genes
New ways of seeing how the sequence changes as we evolve and relationships with other species
Personalised medicines that work on a particular genotype and target diseases more effectively with less side effects
What is genetic engineering
When scientists remove a gene from one organism and insert it into the DNA of another organism
Give an example of how genetic engineering can help diabetics
The gene for human insulin can be put into the plasmid DNA of bacteria. This modified bacteria then produces human insulin which can be used by diabetics
What are GMOs
Genetically modified organisms
How does genetic engineering work
Cutting enzymes are used to remove a gene from DNA. Another gene is stuck in that place by sticking enzymes
What are the pros and cons of using bacterial produced insulin
Pros
It is cheaper than using it from dead animals
Production isn’t affected by diseases in animals
Vegans can use it
Cons
Not identical to human insulin so some people can’t use it
What is a diploid cell
A cell that can 2 copies of chromosomes in its nucleus
How many chromosomes do human diploid cells have
46 and 23 pairs
Which 2 human cells aren’t diploid
Egg and sperm as they get the pair of chromosomes when they fuse in fertilisation
What is mitosis
The process in which cells either replace dead cells or make new ones. To do this they make a copy of each pair of chromosomes then split into 2 daughter cells. Each daughter cell has 1 of the pairs of chromosomes.
What is asexual reproduction and what is it
When organisms reproduce by making genetically identical copies of cells. Bacteria do this and so do so,e plants
What are haploid cells
Cells with only one set of chromosomes rather than 2. They are the egg and sperm in humans
What happens in fertilisation
Sperm and egg fuse to produce a zygote. The zygote is a diploid cell as it has 2 sets of chromosomes
What is an allele
A different version of the same gene. E.g. The gene for eye colour has different alleles such as blue and brown
What is the process of meiosis
This is the process used to make haploid cells. It starts of a diploid cell and the sets of chromosomes are copied. This cell then splits into 2 daughter diploid nuclei. These then split again to make the haploid cells. This means 1 diploid cell makes 4 haploid cells
What are clones
Genetically identical individuals
Some benefits of animal cloning
They guarantee desirable traits such as high quality baby cows
Can be used to make sure offspring have good skills such as for sniffer dogs
Negatives of animal cloning
First large cloned animal died young and had health problems.
How does nuclear transfer work (process of cloning)
The nucleus from a cell from an animal that will be cloned is removed and placed in an egg with no nucleus (enucleated egg) the egg is then stimulated to make it start dividing to make and embryo. This is then implanted into a surrogate mother. Here it will grow and develop with no genetic relation to its surrogate mother
What is a stem cell
A cell that can divide into different types of cells such as blood cells or neurones
What is the different between embryonic stem cells and adult stem cells
Embryonic ones can become any cell whereas adult ones are limited to a few
What is a bone marrow transplant
When bone marrow is taken from a doner and the stem cells are removed and turned into healthy ones needed by a patient. This doesn’t always work as if the doners cells are too different to the patients, the patients cells will destroy them.
How can cloning be used instead of bone marrow treatment
A clone can be made from the cells of a patients skin. This can be used to make an embryo and the embryonic cells can be harvested. These can be turned into the ones that the patient needs. This is better than bone marrow stem cells as there is no chance of it being rejected.
What is genetic code
The order of bases on a strand of DNA
What are amino acids
These are used to make proteins. There are 20 in humans. The order of bases in DNA is used to make amino acids. They are made of 3 bases.
What is transcription
The first process of making proteins. In this process, the DNA in a gene is unzipped, separating the strands. One of the strands acts a template. Complementary bases to the strand link up to make mRNA. This is similar to DNA but has 1 strand and instead of thymine it uses a base called urasyl. It is small enough to move out a nucleus into the cytoplasm.
What is translation
In the cytoplam, the mRNA attaches to ribosomes. These move from one end of the mRNA to the other, decoding the bases in threes called base triplets or codons. A tRNA comes with an amino acid and links with the complementary base, adding the amino acid to the chain of amino acids. The tRNA is then free to get more amino acids. This continues until the mRNA strand is fully decoded.
What is the chain of amino acids called and what happens to it
It’s called a polypeptide and it twists and folds and may link with other polypeptides to become a protein
What determines the protein polypeptide become
The number of amino acids in it and the order of them.
Why is the order of amino acids important and how do it affect proteins and some examples
The order is what causes the chain to fold up in a particular way to make them best suited for their job. E.g. The order of amino acids in keratin makes it for long, strong fibrous molecules and is found in hair whereas molecules such as haemoglobin form globular molecules so they can move around easier
What is a mutation
A change in the sequence of bases in the genetic code
How can mutation affect the shape of proteins
It can change the order of amino acids produced meaning when the polypeptide folds, it makes a different shape which will effect how it works
What are enzymes and what do they do
They are biological catalysts and speed up reactions in the body without being used up or changed
Why are enzymes so important
Without them, reactions wouldn’t take place fast enough in the body for cells to stay alive, meaning you will die
Give two examples of when enzymes are used to breakdown large molecules in cells
In mitosis and meiosis, they break down the DNA strand
In protein synthesis, to join one amino acid to another
What are enzymes in the digestive system used for
Tom. Real down large molecules such as carbohydrates and fats into smaller ones so they can pass acrosss the cell membrane of the gut wall and into the blood.
Why does freezing food slow down decomposition
As soon as the food is removed from the plant or killed, it starts breaking down. When they are frozen, the enzymes don’t work as efficiently so it can’t be broken down as fast
