Genes and Enzymes - Topic 1 Flashcards Preview

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What 4 things do animal and plant cells have in common?

Cell membrane


What 3 differences do animal and plant cells have?

Plant cells have a rigid cell wall
large vacuole


What does a nucleus do?

Contains DNA that controls what the cell does.


What does the cytoplasm do?

gel like substance where most of the chemical reactions happen.


What does the Cell membrane do?

Holds the cell together and controls what goes in and out of the cell.


What does the Mitochondria do?

These are where most of the reactions for respiration take place, this releases energy the cell needs to work.


What does the Cell wall do?

made of cellulose, gives support to the cell.


What does the Large Vacuole do?

contains cell sap a weak solution of sugar and salts.


What does the chloroplasts do?

where photosynthesis occurs. They contain chlorophyll.


What things are in a bacterial cell?

Chromosomal dna
Cell wall


What does the chromosomal dna do?

(One long circular chromosome) controls the cells activities and replication.


What does the Plasmids do?

Small loops of extra dna that aren't part of the chromosome. plasmids contain genes for things like drug resistance and can be passed between bacteria.


What does the Flagellum do?

long hair-like structure that rotates to make bacterium move.


What do microscopes allow us to see?

nuclei, chloroplast, mitochondria


Whats the difference between light microscopes and electron microscopes?

electron microscopes allow us to see smaller things in more detail like the internal structure of mitochondria and chloroplasts and plasmids.


How do you calculate magnification?

Length of image/ Length of specimen.


What is the structure of DNA?

Double helix with sugar phosphate backbone and weak hydrogen bonds.


What are the 4 bases called and which are complimentary?

Adenine - Thymine
Cytosine - Guanine


What is a gene?

Section of DNA


Which scientists contributed to discovering the structure of dna?

James Watson, Francis Crick, Rosalind Franklin, and Maurice Wilkins.


What did Franklin and Maurice find out and how?

They worked out that dna had a helix structure by directing beams of x-rays onto crystallised DNA and looking at the patterns the x-rays formed as they bounced off.


What did Watson and Crick find out and how?

They used the ideas franklin and maurice had along with the knowledge that the amount of adenine + guanine matched the amount of thymine + cytosine, to make a model of the DNA molecule where all the pieces fitted together.


How many amino acids are there?



What are the two stages of protein synthesis?

Transcription and translation


What is transcription?

the 2 dna strands unzip. DNA is used as a template to make mRNA. Then base pairing ensures it's complementary to the other strand.


What is translation?

this occurs after transcription. The mRNA moves out of the nucleus via nuclear pores. in the cytoplasm the mRNA slots into an organelle called a ribosome. Amino acids that match the mRNA code are brought in through the ribosome by molecules called tRNA. The 3 anti codons on the tRNA match up with the corresponding bases on the mRNA which then releases the amino acid. The amino acids join together until you reach a stop codon to form a protein.


Which base is different on RNA to DNA?

T becomes U


Why is the order of amino acids important?

it affects the shape of the protein which determines its function.


What is a mutation?

a change in the DNA base sequence


What effect does a mutation have?

It affects the sequence of amino acids in the protein, which could affect the shape and the function of the protein. This could inturn affect the characteristics of the organism.


What is a harmful mutation?

the mutation causes harm to the organism. A mutation could cause a genetic disorder, for example cystic fibrosis.


What is a beneficial mutation?

The mutation benefits the organism. A mutation could produce a new characteristic that is beneficial to an organism e.g making bacteria resistant to antibiotics.


What is a neutral mutation?

Some mutation are neither harmful nor beneficial e.g they don't affect a proteins function.


What are enzymes?

they are biological catalysts that speed up reactions inside our body.


What is a catalyst?

A catalyst is a substance which increases the speed of a reaction, without being changed or used up.


What are enzymes made of?



What do enzymes inside cells do?

Help with protein synthesis and DNA replication.


What do enzymes outside cells do?

Help with digestion


What is the substrate?

The substrate is the molecule changed in the reaction. It is either split apart or joined to another.


What is the active site?

Where the enzymes acts on the substrate to break it down or join it together. Has a very specific shape so will only work with certain substrates.


What is the lock and key model?

Model showing that the active site and the substrate have complementary shapes just like a lock and key. It creates an Enzyme-Substrate Complex.


What does denature mean?

The active site of the enzyme changes shape and can no longer bind to the substrate.


How does an enzyme become denatured?

An increase in heat permanently changes the shape of the active site.


What is the optimum temperature for enzyme action?

differs for each enzyme the optimum temp for the most important human enzymes is about 37*C


What is the optimum pH for enzyme action?

differs for each enzyme the optimum pH for the most enzymes is about pH 7


how does enzyme substrate concentration affect how enzymes work

Enzymes will work best if there is plenty of substrate available. As the concentration of the substrate increases, so does the enzyme activity. However, the enzyme activity does not increase without end. This is because the enzyme can't work any faster even though there is plenty of substrate available.


What is the human genome project?

Scientists mapped human genes. The idea was to find every single human gene.


What are the advantages of the Human Genome Project?

Predict and prevent diseases
develop new and better medicine
Accurate diagnoses
Improve Forensic science


What are the disadvantages of the Human Genome Project?

Increased stress - if you knew you were susceptible to a nasty disease.
Gene-ism - people with genetic problems might not have children.
Discrimination by employers and insurers


What is genetic engineering?

Changing an organism's genes to alter its characteristics.


How does genetic engineering work?

you cut the desired gene out of one organism using cutting enzymes then cut another gene out of the organism whose characteristics you want to change. then using sticking enzymes you put the gene into that organism. it will then reproduce and have the desired characteristics.


Give 3 examples of how genetic engineering can benefit humans

Produce human insulin
Beta Carotene in golden rice
Herbicide resistant crop plants


What are the advantages and disadvantages of Human insulin

+can be used by vegans
+not dependant on animals
-Produces insulin slightly different so it doesn't suit everyone


What are the advantages and disadvantages of Beta Carotene in golden rice?

+Children get enough vitamin A so they have healthy immune systems
+ Reduce night blindness in some parts of africa
- may escape into other organisms
- some people think that not enough beta carotene to make a difference in health
- GM seeds infertile


What are the Advantages and disadvantages of herbicide resistant crops

+ Reduces amount of crop spraying
+ spray large amounts over field in one go
- Super weeds that are resistant
- loss of biodiversity as fewer weeds survive.


What is Mitosis?

It is used for growth and repair. A sexual reproduction. Daughter cells are clones and diploid. Makes entire copy of all chromosomes.


What is meiosis?

makes gametes (haploid)
sexual reproduction
daughter cells are non identicle


how does mitosis work?

Two genetically identical diploid daughter cells produced.


How does meiosis work?

four non genetically identical haploid daughter cells produced


How does cloning happen

type of asexual reproduction
unfertilised egg cell is enucleated (nucleus removed)
nucleus taken from adult body diploid cell
placed in egg cell then given electric shock to stimulate mitosis
planted in surrogate mother


What are the uses of cloning

help with shortage of organs for transplants
study of animal clones could lead to greater understanding of development of embryo and age-related diseases
help preserve endangered species


what are the problems with cloning

reduced gene pool - one disease could wipe out population
might not live as long
often fails
born with genetic defects
clones mammals immune systems unhealthy sometimes


What are embryonic stem cells

cells in the embryo are all undifferentiated


What are stem cells

unspecialised cells
able to divide to produce either more stem cells or different types of specialised cell


what is the process of becoming specialised called



Where are stem cells found in adult human

bone marrow
aren't as versatile as stem cells in embryo s


What are the benefits of stem cells

cure diseases such as sickle cell anaemia
can replace cells that have been damaged by disease or injury e.g new cardiac muscle helps with heart disease


What are the ethical concerns about using embryonic stem cells

potential human life, said that scientists should find another source of them
others think its more important to cure suffering patients and embryos are often unwanted ones from fertility clinics