B1 - You and Your Genes

Question 1

What are genes?

Answer 1

instructions to control how an organism develops and functions are found in the nucleus of its cells. Describe how to make proteins

Question 2

What are examples of structural and functional proteins?

Answer 2

Structural- collagen

Functional- amylase

Question 3

What are characteristics determined by?

Answer 3

Genetics (eye colour) Many genes work together to form eye colour
Environment (scars)
combination (weight)

Question 4

chromosomes in a pair carry the same genes in the ________ place, but that
there may be _______ versions of genes called alleles

Answer 4

same

different

Question 5

How many alleles does an individual usually have for a gene?

Answer 5

2

Question 6

What is heterozygous?

Answer 6

When the two alleles of a gene are different

Question 7

What is homozygous?

Answer 7

When the two alleles of a gene are the same

Question 8

Why do siblings have similarities?

Answer 8

because of the combination of

maternal and paternal alleles in the fertilised egg.

Question 9

Why do siblings have differences?

Answer 9

different offspring from the same parents can differ from each other because
they inherit a different combination of maternal and paternal alleles

Question 10

an individual with one or both dominant alleles (in a pair of alleles) _______ show the
associated dominant characteristic

Answer 10

will

Question 11

an individual with one recessive allele (in a pair of alleles) ____________ show the associated
recessive characteristic

Answer 11

will not

Question 12

an individual with both recessive alleles (in a pair of alleles) _________ show the associated
recessive characteristic

Answer 12

will

Question 13

What sex chromosomes do human males have?

Answer 13

XY

Question 14

What sex chromosomes do human females have?

Answer 14

XX

Question 15

How is sex determined?

Answer 15

the sex-determining gene on the Y chromosome triggers the development of testes, and that in the absence of a Y chromosome ovaries develop

Question 16

What is genotype?

Answer 16

the genetic make-up of an organism

the combination of alleles

Question 17

What is phenotype?

Answer 17

the observable characteristics that the organism has.

Question 18

How are genetic disorders caused?

Answer 18

Faulty alleles of a single gene

Question 19

What is an example of a genetic disorder caused by dominant alleles?

Answer 19

Huntington’s disease

Question 20

What is an example of a genetic disorder caused by recessive alleles?

Answer 20

Cystic fibrosis

Question 21

What are the symptoms of huntington’s?

Answer 21

– late onset, tremor, clumsiness, memory loss, inability to

concentrate, mood changes

Question 22

What are the symptoms of cystic fibrosis?

Answer 22

thick mucus, difficulty breathing, chest infections, difficulty in digesting food

Question 23

What is a carrier?

Answer 23

a person with one recessive allele (in a pair of alleles) will not show the symptoms of the disorder, but can pass the recessive allele to their children

Question 24

What is pre-implantation genetic diagnosis?

Answer 24

Pre-implantation genetic diagnosis (PGD) is a procedure used on embryos before implantation. Fertility drugs are taken by the female so that several eggs are released and collected by a doctor. These eggs are then fertilised in a Petri dish by sperm, either from the father or a donor. (IVF) Once the embryos have reached the eight-cell stage, one cell is removed from each.
The cells are tested for the allele posing a risk (for example the Huntington’s allele). This is known as PGD. Embryos that don’t contain the unwanted allele are then implanted into the uterus to hopefully create a lower risk, full-term pregnancy.

Question 25

What is predicted testing?

Answer 25

This is used to detect genetic disorders where the symptoms develop later in life, such as Huntington’s disorder. Predictive testing can be valuable to people who have no symptoms but have a family member with a genetic disorder. The results can help to inform decisions about possible medical care.

Question 26

Testing an individual before prescribing drugs

Answer 26

?

Question 27

What are implications that need to be considered in the genetic testing of adults and embryos?

Answer 27

a. risk of miscarriage as a result of cell sampling for the genetic test b. using results that may not be accurate, including false positives and false negatives c. whether or not to have children at all d. whether or not a pregnancy should be terminated e. whether other members of the family should be informed

Question 28

What are implications for testing embryos for embryo selection prior to implantation?

Answer 28

Some believe life begins at conception - destruction of an embryo=destruction of a person While PGD helps reduce the chances of conceiving a child with a genetic disorder, it cannot completely eliminate this risk. In some cases, further testing is needed during pregnancy to ascertain if a genetic factor is still possible. Although genetically present, some diseases only generate symptoms when carriers reach middle age. The probability of disorder development should be a topic of discussion with the healthcare provider.

Question 29

What are the implications of the use of genetic testing by others (such as employers and insurers)

Answer 29

People may feel discriminated against?

Question 30

How do clones occur naturally? (not animals)

Answer 30

bacteria, plants and some animals can reproduce asexually to form clones

Question 31

Why are there sometimes differences between clones?

Answer 31

any differences between clones are likely to be due only to environmental factors

Question 32

When do clones occur naturally in plants?

Answer 32

clones of plants occur naturally when plants produce bulbs or runners

Question 33

When do clones of animals occur?

Answer 33

a. naturally, when cells of an embryo separate (identical twins) b. artificially, when the nucleus from an adult body cell is transferred to an empty unfertilised egg cell

Question 34

What are the different types of stem cells?

Answer 34

a. adult stem cells which are unspecialised cells that can develop into many, but not all, types of cells b. embryonic stem cells which are unspecialised cells that can develop into any type of cell

Question 35

What are the benefits of stem cells being unspecialised?

Answer 35

offer the potential to treat some illnesses

Question 36

When do the majority of cells in multicellular organisms become specialised?

Answer 36

during the | early development of the organism.