Cell Division and Inheritance

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What are Chromosomes?
Really long molecules of DNA
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What is a DNA molecule made from and what does it contain?
A DNA molecule consits of two long strands coiled to form a double helix. It contains All the instructions to put an organism together and make it work
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What is a Gene?
A section of DNA which contains the instructions to make a specific protein
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How many chromosomes do Body cells have?
two sets of 23, 46
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How do cells make proteins?
By stringing amino acids together in a particular order
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What is the structure of DNA called?
Double helix structure
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What is special about DNA?
Almost everyone's DNA is unique, except Identical twins and clones
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What are two uses of DNA fingerprinting?
Forensic Science and Paternity Testing
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What is Mitosis?
The division of body cells to produce new cells
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Why does Mitosis occur?
For growth and repair and in asexual reproduction
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What happens during Mitosis?
The genetic material is copied and then the cell divides once to form two genetically identical body cells
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What is Meiosis?
When a cell divides to form Gametes,
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What are sex cells called?
Gametes
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What happens during Meiosis?
Copies of the genetic material are made, the cell then divides twice to form four gametes each with a single set of chromosomes
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Are the sex chromosomes identical in females?
Yes, they are both X
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True or false, in males the sex chromosomes are identical
False, in males one sex chromosome (Y) is much shorter than the other (X)
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What is an Allele? give an example
Different forms of the same gene for example the gene that controls eye colour has two alleles blue or brown
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What is a Dominant Allele?
An allele which controls the development of a characteristic when it is present on only one of the chromosomes
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What is a Recessive Allele?
•An allele, which controls the development of characteristics only if the dominant allele is not present, is a recessive allele.
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What's a Phenotype?
A description of how a characteristic is expressed, This can be influenced by genetic or environmental factors.
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What is a Genotype?
A description of the alleles an individual possesses for a characteristic.
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What is a Homozygous Genotype?
A genotype with 2 identical alleles
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What is a Heterozygous Genotype?
A genotype with 2 different alleles for a gene
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When do most animal cells differentiate?
At an early stage of development
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When do plant cells differentiate?
Most plant cells can continue to differentiate throughout their life
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Where are the female and male gametes made?
female gametes are made in the ovaries, male gametes are made in the testes
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Why is their variation in sexual reproduction?
Because each gamete is different and when they fuse the new individual will contain alleles from both parents
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What are stem cells?
Undifferentiated cells, they can develop into any kind of cell depending on the instructions they are given
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Where are stem cells found?
Early human embryos, bone marrow, umbilical cords
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What are stem cells used for? give an example
Medicine uses adult stem cells to cure diseases such as blood diseases which can be treated by bone marrow transplants
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What can scientists do with embryonic stem cells?
They can extract them and grow them into new different types of cell
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Why are some people for/ against Stem cell research?
Against: human embryos shouldn't be used since each one is a human life, For: curing existing patients is more important than the rights of embryos, embryos used can be unwanted ones from fertility clinics (saving them from being destroyed)
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Who is Gregor Mendel and what did he do?
An Austrian monk, he did genetic experiments with pea plants and discovered how characteristics in plants were passed on from one generation to the next
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What is Monohybrid inheritance?
When a characteristic is determined by just one pair of alleles
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What is Cystic Fibrosis and what is it caused by?
A genetic disorder of the cell membranes producing thick sticky mucus in the air passages and the pancreas caused by a recessive allele carried by about 1 in 25 people
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What is Polydactyly and what's it caused by?
A genetic disorder where a baby's born with extra fingers or toes, caused by a dominant allele
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What is Embryo Screening?
Where people can check their embryos to see if they have any genetic disorders, during IVF before the embryo is implanted a cell can be removed and analysed, embryos with 'good' alleles would be implantec, those with 'bad' alleles would be destroyed
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What are the reasons against Embryo Screening?
Everyone may start screening their embryos to pick the most 'desirable' one, the rejected embryos are destroyed - they could have developed into humans, implies people with genetic problems are 'undesirable' causing prejudice, screening is expensive
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What are the reasons for Embryo Screening?
It will help stop people suffering, there are laws to stop it going too far, during IVF most of the embryos are destroyed anyway- screening just allows the selected one to be healthy, treating disorders costs the government and taxpayer lots of money
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Other cards in this set

Card 2

Front

What is a DNA molecule made from and what does it contain?

Back

A DNA molecule consits of two long strands coiled to form a double helix. It contains All the instructions to put an organism together and make it work

Card 3

Front

What is a Gene?

Back

Preview of the front of card 3

Card 4

Front

How many chromosomes do Body cells have?

Back

Preview of the front of card 4

Card 5

Front

How do cells make proteins?

Back

Preview of the front of card 5
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