Science B1

B1 Science Section:

Chromosomes, DNA, Genes, Proteins, Mendell, Genetic Engineering, Genetic Testing, Prokaryotic and Eukaryotic Cells.

Name 3 Inherited Factors.
Anything Including: natural eye/hair/skin colour, ear lobes, blood type, genetic conditions (Huntingtons disease, cystic fibrosis etc)
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Name 3 Environmental Factors.
Anything Including: accents, scars, language, tatoos, heath issues
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Name 3 factors that are inherited and environmental.
Personality traits, intelligence, height, BMI, allergies, freckles
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What is a Genotype?
The genetic make-up of an organism. EG: the combination of alleles
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What is a Phenotype?
the observable, physical characteristics that an organism has. This is often related to a particular gene; physical appearance
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What are Chromosomes?
They are made of DNA (deoxyribose nucleic acid) carry the genetic code that determines the characteristics of a living thing.
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Where are chromosomes found?
In the nucleus of every eukaryotic cell
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How many chromosomes are there?
23 pairs and 46 in total
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How is the sex of the baby determined?
When sex cells form, the pairs of sex chromosomes (** and XY) are separated. Females carry **, males XY. This means: all normal egg cells produced by a human ovary have an X chromosome half the sperm carry an X chromosome, and half a Y
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What is a Gene?
A short length of DNA which codes for characteristics and traits
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What do genes do and how?
Each gene codes for a specific protein by specifying the order in which amino acids must be joined together
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What are alleles?
Different forms of the same gene
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What is a dominant allele?
An allele that is always expressed when present
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What is a recessive allele?
An allele which can be masked by another allele and is only expressed when two copies are present
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What does Homozygous dominant mean?
Having two identical dominant alleles ( EG: HH)
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What does Homozygous recessive mean?
Having two identical recessive alleles (EG: hh)
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What does Heterozygous mean?
Having different alleles (EG: Hh)
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What was the human genome project?
A project to mainly work out the order or sequence of all the three billion base pairs in the human genome
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How was human genome sequencing done?
A large DNA molecule is made into smaller fragments (fragmentation) and is sequencedand the assembly of overlapping DNA sequencing causes a final assembled sequence
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Name 3 Pros of the human genome project.
Anything Including: Improved genetic testing, new gene therapy treatments, new knowledge of how humans have evolved, Personalised medicines, Location of genes that might be linked to increased chances of inheriting a diseasew
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What is Genetic Engineering?
When selected genes are artificially transferred from one living organism to another to change its genome
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What is a genome?
all DNA, chromosomes, genes etc
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What is the process of genetic engineering?
DNA with the desired gene is removed from the cell and the enzyme cuts out the gene and insert it into a DNA vector (taken from a bacterium). The bacteria reproduce.
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Name 3 advantages of GM crops.
Anything Including: improves the growth rate of plants, can be modified to produce their own pesticide chemicals, longer shelf lives, improves food value, can grow in a variety of conditions
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Name 3 disadvantages of GM crops.
Anything Including: No-one knows the long term effects, insects may become pesticide resistant, genes from GM plants may spread into countryside, GM crops aren't fertile
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What is Genetic Testing?
Analysing a person’s DNA to see if they carry alleles that cause genetic disorders
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Name 3 Genetic Diseases that can be tested for.
Anything Including: red/green colour blindness, haemophilia, downs syndrome, sickle cell disease, cystic fibrosis
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Name 3 reasons for Genetic Testing.
Anything Inclding: An individual already has a child with a birth defect and or genetic disease, a woman has delivered a stillborn with signs of a genetic disease, The woman is over 34, a close relative has a genetic disease
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What is Amniocentesis?
A small amount of the amniotic fluid surrounding the baby in the womb is removed by passing a very fine needle through the mother’s abdomen
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What are the potential risks of having an amniocentesis?
About 1 in 100 women (1%) miscarry and 1 in 1000 women will have a serious infection
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What is CVS?
Chronic villus sampling is when a small sample of tissue is removed from the placenta using a fine needle
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What are the potential risks of having a CVS?
About 2 in every 100 women (2%) miscarry and Less than 1 in 1000 women get a serious infection
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What are the potential risks of having a CVS?
About 2 in every 100 women (2%) miscarry and Less than 1 in 1000 women get a serious infection
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What is a Prokaryote?
Unicellular organisms that do not have membrane-bound organelles. EG: bacteria.
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What do prokaryotic cell have?
they have a single circular chromosome in the centre of the cell that holds all the genes needed for that bacterium
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What are plasmids?
Bacteria also have extra circles of DNA called plasmids that contain additional genes (EG: antibiotic resistance) which may increase a bacterium’s chance of survival.
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What is a Eukaryote?
Cells that have membrane-bound organisms like mitochondria and nuclei. EG: Animals, plants and fungi.
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What do eukaryotic cells have?
They have DNA in the linear chromosomes that is tightly coiled and packaged around special proteins.
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What is DNA?
(Deoxyribo) nucleic acid is the genetic information which form chromosomes
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What is a Helix?
Tightly coiled up DNA twisted in spirals
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What is a double helix?
Two strands coiled together. There are chemical cross-links between the two strands, formed by pairs of bases
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What form the sides of the bases?
Sugars (S) and Phosphates (P)
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What is a Protein?
Each gene codes for a protein and each protein has its own number and sequence of amino acids. This allows it to carry out a particular function
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What do proteins do?
Proteins are made of long chains of amino acids from which there are 20 different types of amino acid that make proteins
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What is Transcription?
The first part of the process of making a protein. It takes place inside the cell nucleus and involves copying the DNA
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What is the process of Transcription?
1. The DNA in a gene unzips so that both strands are separate – one strand is used as a template. 2. Complementary bases attach to the strand being copied 3. Base T is replaced with U 4. This forms a strand of messenger RNA (mRNA)
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What is the process of Translation?
1. The mRNA attaches to a ribosome that reads it 2. The ribosome decodes the mRNA in groups of three 3. The tRNA is specific to an amino acid that it collects and returns to the mRNA 4. the amino acids are lined up to match the mRNA 5. a polypeptid
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What is Translation?
It takes place in the ribosomes that are found in the cytoplasm and is where the messenger RNA is 'interpreted' and the new protein formed
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Other cards in this set

Card 2


Name 3 Environmental Factors.


Anything Including: accents, scars, language, tatoos, heath issues

Card 3


Name 3 factors that are inherited and environmental.


Preview of the front of card 3

Card 4


What is a Genotype?


Preview of the front of card 4

Card 5


What is a Phenotype?


Preview of the front of card 5
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