B2.1 Flashcards
What organelles do plant and animal cells have in common
Cell membrane
Cytoplasm
Nucleus
Mitochondria
What do plants have but animal cells don’t
Cell wall
Large vacuole
Chloroplasts
What does the cell membrane do
Separates the contents of the cell From the outside and controls the movement of substances such as oxygen and glucose coming into and out of the cell
What does the cytplasm di
The reactions needed for life are carried out in the cytoplasm. Also contains all the organelles
What does nucleus do
Organelle that contains all the DNA, genetic material. Also controls the activities of the cell, like the brain
What does mitochondria do
Where respiration occurs, reacts oxygen and glucose together to release energy
What does the cell wall do and made of
Made of cellulose and supports the cell so it can keep its shape
Large vacuole
Filled with cell sap that supports the cell and keeps it
Chloroplasts
Organelles containing chlorophyll that absorbs light energy that is used for photosynthesis
What are the parts of a bacteria cell
Chromosomal DNA Cell membrane Plasmid DNA Cell wall Flagellum, not always though
What is the chromosomal DNA
Large loop of DNA containing most of the genetic information. Not neatly packaged like it is in human or plant chromosomes
What is plasmid DNA
Small loops containing extra genetic material
What does the flagella do
On the outside of the cell and allows the bacteria to move
What are chromosomes
A string of genes that contains instructions for young ur body
What are genes
A single instruction in a chromosome consisting of DNA
What is DNA
A long coiled molecule that can unzip and copy itself when a cell divides
What are the two strands of DNA held by
Held together at regular intervals by chemicals called bases
What are the complimentary bases and how are they he,d
Adénine thymine
Cytosine guanine
Held together by seal hydrogen bonds
What did Maurice Wilkins and Rosalind franklin do
They were studying the structure of DNA using x rays, franklin directed beams of x rays at purified DNA and used the photos to see how the molecule scattered the x rays, from the patterns, she could see atoms in DNA molecule were arranged
What did James Watson and Francis crick do
They were trying to build a model of the structure of DNA using data from other scientists. They used the x ray results from franklins photos which Wilkins had given them without franklins permission. With this detail, Watson and crick were able to build the double helix model
What was the hgp
The human genome project was an international effort involving scientists from 18 countries sharing there latest developments with each other to help each other, after 13 years, the HGP was complete and scientists had worked out the order of 3 billion base pairs that make up the human genome, it showed everyone had 99.9% of DNA in common
What is a genome
All the genetic infomation of an organism with the order of all its bases
What are the benefits of the HGP
Improved testing for genetic disorders. Easier to see if people are carrying a faulty allele
New ways of finding genes that may increase the risk of illnesses such as Alzheimer’s and heart disease
New treatments and cures for disorders, gene therapy, where scientists mend or replace faulty genes
New ways to see how we have evolved from other organisms and our evolutionary relationships
Personalised medicine that work with a particular genotype and targets diseases more effectively with less side effects
What is genetic engineering
The name of the process in which a gene is removed from one organism and placed into the genetic information of another organism
Benefits genetic engineering for diabetics
Human insulin gene can be inserted into bacterial plasmid DNA so the bacteria produces human insulin. This is good as it means it no longer has to be extracted from dead cattle so vegans can use it. However, there are minute changes from the bacterial and human insulin so it doesn’t suit everyone.
What two types of enzymes are used in genetic engineering
Restriction enzymes, cutting
DNA ligase, sticking enzymes
How can bacteria be made to make human insulin
Insulin gene from human removed by restriction enzymes and plasmid DNA of bacteria cut. Ligase enzyme sticks the insulin gene into the plasmid DNA of the bacteria, bacteria now makes human insulin
What is vitamin a for
Making sure the immune system works properly, lack of it can cause blindness or even death
Why is beta carotene important
It’s needed by us so we can produce vitamin a
What method of division is mostly used by our bodies for growth and repairing cells
Mitosis
What type of cell division do gametes use
Meiosis
What happens in mitosis
Chromosomes replicate in nucleus of the diploid cell so now 46 pairs. Nucleus and then whole cell divides into two, each new cell has one copy of each pair of chromosomes so 23 pairs each. They are both diploid daughter cells and genetically identical to parent cell
What is asexual reproduction
Where new complete individuals are produced by one parent, mitosis and bacterial division are examples
What is in sexual reproduction
New individuals made from two parent cells, gamètes that fuse in fertilisation, turning two haploid cells into one diploid zygote cell
What happens in meiosis
Chromosomes replicate then rest of cell splits into two diploid cells, these diploid cells then split without replicating chromosomes so each one has no pair of chromosomes and 23 unique ones. So in total there are 4 haploid cells made from one diploid
Why aren’t cells produced from meiosis genetically identical to their parents like in mitosis
In a diploid cell, there are two of the same chromosome, they may have slightly different genes, alleles, so they aren’t the same. In mitosis, each daughter cell gets both of those chromosomes so they are identical. However, in meiosis, during the second division, the pair of chromosomes a split so each daughter cell only has one of each chromosome instead of two so they aren’t the same as the parent
What are clones
Individuals that are genetically identical to another
Benefits of cloning
Guarantees desirable traits are passed on.
Genetically modified animals such a high milk producing cows can be cloned to make sure the new cow has the same trait
What is and how does nuclear transfer work
Nucleus taken from cell of to be cloned animal. Nucleus removed from another egg cell of the same species but different organism. Nucleus from to be cloned animal implanted into the enucleated egg cell. This cell now has a nucleus and is stimulated to divide and become an embryo. The embryo is then implanted into the uterus of a surrogate mother. Here it will develop until it is born. It has no genetic relation to surrogate mother
What are special about stem cells
It can divide to produce more stem cells or it can differentiate into a specialised cell such as a neurone, muscle cell or a skin cell. Once it has differentiated, it can no longer differentiate into another.
What’s the difference between an adult stem cell and an embryonic stem cell
Adult ones can only differentiate into a few cells but embryonic cells can become almost any type of human cell
One use of embryonic stem cells
Clone a patient using their cells to produce a cloned embryo of them, extract the embryonic stem cells and use them to make new heart muscle cells for the patient and put it into partirent. Better than transplant as there is no chance of rejection
What is the genetic code
Code of an organism formed by the order of bases in its DNA
What are amino acids
Something used to make proteins in humans, there are twenty different ones in humans
What is protein synthesis
The process of creating proteins buy building chains of amino acids based on the sequence of bases in the DNA
What identifies each amino acid
The group of bases its linked to, e.g. CGA may link to one acid and AUU to another
What happens in transcription
This occurs in the nucleus. The DNA unzips itself by breaking the weak hydrogen bonds. One side of the strand acts as a template and the complimentary bases to the strand link up to make a molecule of mRNA. mRNA has the same order of bases as the other side of the DNA but instead of thymine, it has uracil. The mRNA then leaves the nucleus and goes into the cytoplasm
What happens in translation
mRNA attaches to ribosome and the ribosome moves along it, decoding the bases in threes known as base triplets or codons. Complimentary tRNA that compliment the codons come along with an amino acid attached and adds the amino acid to the chain. The tRNA is then free to collect another amino acid. The next tRNA complimentary to the next codons then does the same thing. This continues until the whole mRNA has been decided
What happens once the mRNA is fully decoded
The strand of amino acid is called a polypeptide and it then twists and folds and may join with other polypeptides to become a protein
Why are enzymes specific to one reaction
The order of its amino acids causes it to form a particular shape that only works in one kind of reaction
What is a mutation
A change in the order of bases in the genetic code.
What can be the affect of mutations
It might not have an effect on the order of amino acids so the protein might not change but if it does change the order of amino acids, the protein will fold a different way and may be different and not function so well
What causes sickle cell disease
The order of bases for forming haemoglobin is mutated. This means the amino acid chain isn’t correct so the protein isn’t formed properly and is in the wrong shape. This makes the protein molecules stick together in long fibres, making the sickle shape of the blood cell
What causes albinos
The colour of your skin and hair is determined by a protein called melanin. Melanin is made using the enzyme tyrosinase. Albinos have a mutation in the gene for tyrosinase so can’t make melanin so they are very white
What do enzymes do and why are they so important
They are biological catalysts that speed up reaction in the body without being used up. If they weren’t present, some reactions may be too slow to sustain life
How do enzymes help in DNA replication for meiosis and mitosis
They unzip the weak hydrogen bonds in the DNA strand. Complimentary bases line up with each side of the strand and another enzyme joins them together so there are two grands of DNA. This makes two identical strands of DNA molecules. The enzymes are unchanged and can continue to do this wherever and whenever it’s needed
How does concentration of substrate affect enzyme rate of reaction.
Increases it up to the point where concentration of substrate is no longer the limiting factor as there are now not enough enzymes to carry on increasing rate of reaction as they’re all being used
What is the lock and key hypothesis
Enzymes have a specifically shaped active sight and act as the lock, only a specific shape will fit into it and this are its species substrates, the key. The enzyme holds the substrate tightly in place so bonds can form between the substrates quickly to make the new molecule
What does changing the pH or temperature do to enzymes
It dénaturés them, causes the active sight to change shape so the substrates no longer fit as well if at all so the enzyme doesn’t work properly
