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Flashcards in Topic 6 Deck (34)
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1
Q

What is DNA

A

A polymer made of two strands colied making a double helix. The polymers are made up of lots of repeating units called nucleotides

2
Q

What is a gene

A

A small section of DNA found on chromosomes, each codes for a particular sequence (what order) of amino acids which are put together to make a specific protein. Only 20 amino acid are used.

3
Q

What is a genome

A

Entire set of genetic material in an organism.

4
Q

Hhy is understanding the human genome important

A

Allows scientists to identify links to different diseases (which ones are inherited). It can also trace migration

5
Q

What does each nucleotide consist of

A

A sugar, a phosphate group and one ‘base’. These form a backbone to the DNA strands. They are complementary bases with C-G or A-T which decides the order of amino acids. Each amino acid is coded for by a sequence of three bases in the gene.

6
Q

What is mRNA and ribosomes effect of protein synthesis

A

Molecule which gets code from DNA to ribosomes. Proteins are synthesised on ribosomes, according to a template. Carrier molecules bring specific amino acids to add to the growing protein chain in the correct order.

7
Q

Functions of protiens

A

Enzymes
Hormones
Structral Protiens

8
Q

What do parts of DNA that don’t code protien effect

A

Some of these non-coding parts switch genes off and on so they control wether or not a gene is expresses.

9
Q

What is the structure of a completed protin chain

A

When the protein chain is complete it folds up to form a unique shape. This unique shape enables the proteins to do their job as enzymes, hormones or forming structures in the body such as collagen.

10
Q

How do mutations occur

A

Mutations occur continuously. Most do not alter the protein, or only alter it slightly so that its appearance or function is not changed.

11
Q

How does mutations effect enzymes

A

A few mutations code for an altered protein with a different shape. An enzyme may no longer fit the substrate binding site or a structural protein may lose its strength.

12
Q

What are different types of mutations

A

Insertions - when a new base is inserted (may have a knock-on effect)
Deletions - random bases deleted from DNA base sequence
Substitutions - random base is changed

13
Q

What does the father pordice is sexual reproduction

A

Gametes by meiosis

14
Q

What is exual reproduction

A

Involves the fusion of male and female gametes. Because there are two parents, the offspring contain a mixture of their parent’s genes.

15
Q

What does sexual reproduction lead to

A

sexual reproduction there is mixing of genetic information which leads to variety in the offspring. The formation of gametes involves meiosis.

16
Q

What does asexual reproduction involve

A

Asexual reproduction involves only one parent and no fusion of gametes. There is no mixing of genetic information. This leads to genetically identical offspring (clones). Only mitosis is involved.

17
Q

What is mitosis

A

An ordinary cell makes a new cell by dividing in two

18
Q

What are gametes

A

They only have one copy of each chromosome so that when gamete fusion takes place, you get the right amount of chromosomes agian.

19
Q

how meiosis halves the number of chromosomes in gametes

A
  • first the cell duplicates its genetic information forming two armed chromosomes (each arm being an exact copy of the other).
  • after replication the chromosomes arrange into pairs.
  • the first division the chromosomes pairs line up in the centre of the cell
  • the pairs pull apart so each new cell only has one copy of each chromosome (father’s and mother’s)
  • in second division the chromosmes line up again in the centre of the cell. The arms are pulled aprt.
  • you get four gametes, each with single set of chromosomes in it. Each gamete is gentically different as the chromosomes are all shuffled up.
20
Q

How does the cell produced by gamete fusion replicate itself

A

After two gametes fuse the resulting new cell divides by mitosis and repeates many times to form an embryo. The cells then diffrinciate and become specialised.

21
Q

Some characteristics are controlled by a single gene, such as:

A

fur colour in mice; and red-green colour blindness in humans. Each gene may have different forms called alleles.

22
Q

A dominant allele

A

A dominant allele is always expressed, even if only one copy is present.

23
Q

A recessive allele

A

A recessive allele is only expressed if two copies are present (therefore no dominant allele present).

24
Q

What do alleles presented/genotype do

A

The alleles present, or genotype, operate at a molecular level to develop characteristics that can be expressed as a phenotype.

25
Q

If the two alleles present are the same the organism is …

A

homozygous for that trait

26
Q

What is heterozygous

A

If its two alleles are for a particular gene are different

27
Q

What are Most characteristics are a result of

A

multiple genes interacting, rather than a single gene.

28
Q

What is your genotype

A

The combination of alleles you have (allele that is present in an individual).

29
Q

What is your phenotype

A

Characteristics you have to determine the genotype

30
Q

What is Polydactyly

A

(having extra fingers or toes) is caused by a dominant allele.

31
Q

What is cystic fibrosis

A

(a disorder of cell membranes) is caused by a recessive allele. It results in the body producing a lot of thick sticky mucus in the air passages and pancreas

32
Q

How does IVF detect inherited disorders such as cystic fibrosis

A

Embryos are fertilised in a lab and then implanted into mother’s womb. Beofre being implanted. It’s possible to remove a cell and analyse its genes. It is also possible to get DNA from the embryo in the womb.

33
Q

For embyonic screening

A

It will help people stop suffering.
Costs Government and taxpayers lots of money
Laws to stop it going to far (cannot select sex of baby).

34
Q

Against embryonic screening

A

Implies people are undesirable with genetic problems
It is expensive
Screening could lead to terminate pregnancy