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Biology > B1- You and your genes > Flashcards

B1- You and your genes Flashcards

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1
Q

How many chromosomes does the human nucleus cell have?

A

The genetic material in the nucleus is arranged into chromosomes. The human cell nucleus has 23 pairs of chromosomes.

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2
Q

What is DNA?

A

Each chromosome is one very long molecule of DNA - that is coiled up.

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3
Q

What is a gene?

A

A gene is a short length of a chromosome.

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4
Q

What do genes control?

A

Genes control the development of different characteristics ( e.g. Hair colour) and how an organism functions.

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5
Q

What are different versions of the same gene called?

A

The different versions of the same gene are called alleles.

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6
Q

Describe genes?

A

Each gene is a code for making a certain protein. Having different versions of proteins means that we end up with different characteristics.

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7
Q

What are the two types of proteins?

A

Structural proteins- They are part of our skin, hair, blood and the cytoplasm in our cells.

E.g. Collagen which is found in our bones and tendons.

Functional proteins- They are found in enzymes that help with digestion by breaking down food molecules.

E.g. Amylase is a digestive enzyme that breaks starch to maltose.

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8
Q

What is an organisms genotype?

A

Genotype is all of the genes the organism has.

The genetic make up.

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9
Q

What is an organisms phenotype?

A

Phenotype is all the characteristics the organism displays.

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10
Q

What characteristics are caused by environmental factors?

A

Environmental factors control some characteristics. They don’t have anything to do with genes. For example, cuts and scars.

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11
Q

How many chromosomes do sex cells have?

A

Sperm and the egg contain just 23 single chromosomes.

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12
Q

What happens when the sperm fertilises the egg?

A

During sexual reproduction- the 23 chromosome in the sperm combines with the 23 chromosomes in the egg.

The fertilised egg then has 23 PAIRS of chromosomes.

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13
Q

Why do children resemble their parents but are never identical?

A

Half the child’s chromosome comes from each parent. This means the child gets some of their alleles from each parent. This is why they look similar to their parents.

However, they don’t look identical because they haven’t got all the same alleles.

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14
Q

How are genes randomly put together to make eggs and sperms?

A
  • The 2 chromosomes in a pair are never identical because they have different alleles.
  • So, when they go into 2 different sex cells each of the two cells gets different alleles.
  • Each of the 23 chromosome pairs separates independently.
  • Thus, there are millions of different chromosome combinations that can be produced from the separation of 23 pairs.
  • This means all sex cells produced by an individual will be all genetically different.
  • A woman’s egg can be fertilised by any one of millions of sperm.

This means the chance of two siblings looking identical is minuscule.

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15
Q

What are homozygous and heterozygous?

A

Homozygous- you have 2 alleles the same for a particular gene.

Heterozygous- you have 2 different alleles for that particular gene.

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16
Q

What are dominant and recessive alleles?

A

Dominant alleles always display their characteristic. Overcomes the recessive allele.

• To show the characteristics caused by a recessive allele- both alleles for a gene have to be recessive.

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17
Q

How are dominant and recessive alleles represented in genetic diagrams?

A

Dominant alleles have capital letters. Recessive alleles have small letters.

18
Q

Genetic diagrams?

A

(Look at punnet squares and genetic diagram)

19
Q

What is the gene that controls gender?

A
  • All men have XY the Y causes them to develop male characteristics.
  • All woman have XX the lack of Y chromosome causes female characteristics.
20
Q

What does the Y chromosome cause?

A

The protein causes the development of testes instead of ovaries. The testes then produce male sex hormones which make the male reproductive system to develop.

If Y chromosome is not produces the female reproductive system is produced.

21
Q

Where is genetic material?

A

Cells in our body have a nucleus- this is where our genetic material is.

22
Q

What is cystic fibrosis?

A

Cystic fibrosis is a genetic disorder of the cell membrane caused by faulty recessive allele.

23
Q

What are the symptoms of cystic fibrosis?

A
  • Thick sticky mucus
  • Breathing difficulty
  • Chest infections
  • Difficulty in digesting foods
  • Early onset
24
Q

Statistics of cystic fibrosis?

A
  • The recessive allele is carried by 1 person in 25.
  • People with one copy of the allele won’t show the symptoms (because it is a recessive allele) are called “carriers”.
  • For a child to have a chance of inheriting, both parents must be carriers or sufferers.
25
Q

What is Huntingtons disease?

A

Huntingtons disorder is a genetic disorder caused by a dominant allele.

26
Q

What are the symptoms of Huntingtons disease?

A
  • tremors ( shaking)
  • poor concentration
  • mood changes
  • memory loss
  • clumsiness
  • late onset
27
Q

Statistics of Huntingtons disease?

A
  • The dominant allele means there is 50% chance of each child inheriting the disorder if one parent is a carrier.
  • The carrier is going to be a sufferer to because it is a dominant allele.
28
Q

What is pre implantation genetic diagnosis?

A

When embryos are produced using IVF doctors can test the embryo to check if they have any genetic disorders.

Healthy embryos are implanted into the womb and embryos with the disease are discarded.

29
Q

Can children and adults be tested for genetic disorders?

A

Children and adults can be tested before certain drugs are prescribed to them. This can show how a drug is likely to affect an individual.

30
Q

Issues surrounding genetic testing?

A
  • Not 100% accurate - misinterpretation of results.
  • ” false positive” and “ false negative” results given to people.
  • Not 100% safe. Miscarriage in 0.5 to 1% of cases.
  • Terminate pregnancy could be an option for couples.
  • Discrimination - employers won’t give ill people the job.
  • insurance companies will refuse life insurance to people who are suffering from illness.
31
Q

What are clones?

A

Clones are genetically identical organisms- they have the same genes and the same alleles.

32
Q

What is asexual reproduction?

A

Asexual reproduction mean one parent produces genetically identical offspring.

33
Q

Examples of asexual reproduction?

A
  • Bacteria- they divide into two and and multiply quickly.
  • Runners- produce horizontal stems called runners and produce clones at the tips.
  • female greenfly- they lay eggs which develop into identical females, but can reproduce sexually when they want.
34
Q

When can differences occur in clones?

A

Environmental factors- one clone might get more food than the others therefore will be better nourished and as a result will be taller than the others.

35
Q

What happens when an embryo splits?

A

A fertilised egg develops as normal. Occasionally, the embryo splits into two and two separate embryos begin to develop. The two embryos are genetically identical- so identical twins are born.

36
Q

How do scientists make animal clones in a lab?

A
  • the nucleus of an egg cell is removed- leaving the egg without genetic information.
  • the nucleus from and adult donor cell is inserted in its place.
  • the cell is stimulated so it starts dividing as a normal embryo.
  • the embryo produced is genetically identical to the donor cell.
37
Q

What are stem cells?

A

Most cells in multicellular organisms become specialised during early development of the organism.

Some cells are unspecialised they can develop into different kinds of cells. These are stem cells.

38
Q

What are embryonic stem cells?

A
  • they are unspecialised cells found in embryos.
  • the stem cells are removed from the embryo then the embryo is destroyed.
  • they have the potential to turn into ANY kind of cell.
39
Q

What are adult stem cells?

A
  • they are unspecialised cells found in adult animals.
  • they can maintain and repair old and damaged tissues
  • they can turn into MANY but not ALL kinds of cells.
  • they are removed safely from the bone marrow. And no embryos are destroyed.
40
Q

Can adult stem cells treat illnesses?

A

Medicine already contains adult stem cells to cure disease.

For example, sickle cell anaemia can be treated by bone marrow transplants. Bone marrow contains stem cells. They can replace faulty blood cells with new ones.

41
Q

Can embryonic stem cells treat illnesses?

A

Embryonic stem cells could be used to replace faulty stem cells in sick people.

For example, insulin producing cells for people with diabetes, nerve cells for people who are paralysed by spinal injuries and so on.

However, these treatments are being researched so they are not available yet.

Biology (7 decks)

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