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‼️Biology‼️ > Topic 3 - Genetics > Flashcards

Topic 3 - Genetics Flashcards

1
Q

What is meiosis?

A

Meiosis is a type of cell division. In humans meiosis only happens in the reproductive organs ( ovaries and testes)

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2
Q

What are produced due to meiosis?

A

Gametes (sex cells)
Meiosis produces four daughter cells, each with half the number of chromosomes and this results in the formation of genetically different haploid gametes

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3
Q

What’s meant by reproduction?

A

Reproduction is about passing on your DNA to the next generation

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4
Q

What is DNA?

A

DNA strands are polymers. This means they’re made up of lots of repeating units joined together.

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5
Q

In terms of DNA, what are the four different bases?

A

Adenine A
Thymine T
Cytosine C
Guanine G

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6
Q

What is a DNA molecule like?

A

A DNA molecule has two strands coiled together in the shape of a double helix. Each base links to a base on the opposite strand in the helix.

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7
Q

What is the complementary base pairing?

A

A(adenine) always pairs up with T(thymine)

C(cytosine) always pairs up with G(guanine)

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8
Q

What are the complementary base pairs joined together by?

A

Weak hydrogen bonds

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9
Q

What is a chromosome?

A

Long, coiled up molecules of DNA. Which are found in the nucleus of eukaryotic cells

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10
Q

What is a gene?

A

A section of DNA on a chromosome that codes for a particular protein. The sequence of bases in the gene determines what protein is produced

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11
Q

What’s a genome?

A

All of an organism’s DNA makes up its genome

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12
Q

How is DNA extracted from fruit?

A

1) Mash some fruit and put them in a beaker containing a solution of detergent and salt. (The detergent will break down the cells membranes to release the DNA & the salt will make the DNA stick together)
2) Filter the mixture to get the froth and big, insoluble bits of cell out
3) Gently add some ice-cold alcohol to the filtered mixture
4) The DNA will start to come out of solution as it’s not soluble in cold alcohol. It will appear as a stringy white precipitate that can be fished out with a glass rod

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13
Q

What is an allele?

A

Alleles are different versions of the same gene. All genes exist in different versions called alleles. You have two alleles of every gene in your body

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14
Q

What controls the characteristics you develop?

A

The genes you inherit control what characteristics you develop. Different genes control different characteristics - some are controlled by a single gene however most are controlled by several genes interacting

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15
Q

What is meant by homozygous?

A

If an organism has two alleles for a particular gene that are the same

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16
Q

What’s meant by heterozygous?

A

If it’s two alleles for a particular gene are different

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17
Q

What are dominant alleles?

A

Dominant alleles overrule recessive alleles. Shown with a capital letter

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18
Q

What’s a recessive allele?

A

an allele that produces its characteristic phenotype only when its paired allele is identical. Shown with a small letter

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19
Q

What must happen for an organism to display a dominant characteristic?

A

To display a dominant characteristic, an organism can have either two dominant alleles for a particular gene or one dominant and one recessive allele for that gene.

20
Q

What must happen for an organism to display a recessive characteristic?

A

Both of its alleles must be recessive

21
Q

What’s your genotype?

A

The combination of alleles you have

22
Q

What’s your phenotype?

A

The characteristics you have determined by your alleles. Different combinations of alleles give rise to different phenotypes

23
Q

What’s a zygote?

A

a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum

24
Q

What is a monohybrid inheritance?

A

The inheritance of a single characteristic

25
Q

What do monohybrid cross’s show?

A

They show how recessive and dominant traits for a single characteristic are inherited

26
Q

What are genetic diagrams?

A

Genetic diagrams are used to show the possible outcomes of a particular cross. A dominant allele is shown by a capital letter, and a recessive allele by a lower case letter.
They can show how sex is determined in humans

27
Q

What chromosomes do men have?

A

Males have an X and a Y chromosome (XY) - the Y chromosome causes the male characteristics

28
Q

What chromosomes do women have?

A

Females have two X chromosomes (XX) - the XX combination allows female characteristics to develop

29
Q

What decides sex determination?

A

All eggs have one X chromosome, but a sperm can have either an X chromosome or a Y chromosome. So sex determination in humans depends on whether the sperm that fertilises an egg carries an X or a Y

30
Q

What’s a pedigree chart needed for?

A

Doctors can use a pedigree analysis chart to show genetic disorders are inherited in a family. They can use this to work out the probability (chance) that someone in a family will inherit a condition. This is called pedigree analysis.

31
Q

How do you calculate and analyse outcomes from monohybrid crosses and pedigree analysis for dominant and recessive traits?

A

You use probabilities, ratios and percentages -
if 3 of the offspring are normal compared to the 1 who isn’t there’s a 3:1 ratio. In other words, there’s a 3 in 4 (75%) probability of normal offspring and a 1 in (25%) probability of not normal

32
Q

What are phenotypic features due to?

A

Most phenotypic features are the result of multiple genes rather than single gene inheritance

33
Q

What’s produced as a result of sexual reproduction?

A

Sexual reproduction produces genetically different cells. Sexual reproduction is where genetic information from two organisms is combined to produce offspring which are genetically different to either parent

34
Q

How are gametes haploid cells?

A

As they only contain half the number of chromosomes of normal cells

35
Q

What happens at fertilisation?

A

A male gamete fuses with a female gamete to produce a fertilised egg (zygote). The zygote then undergoes cell division and develops into an embryo which inherits characteristics from both parents

36
Q

What’s meant by variation?

A

Variations are the difference within a species. These differences can be genetic or environmental

37
Q

What is genetic variation?

A

Genetic variation within a species is caused by organisms having different alleles which can lead to differences in phenotype. It can be caused by new alleles arising through mutations. Sexual reproduction causes genetic variation as it results in alleles being combined in lots of different ways in offspring

38
Q

What are environmental variations?

A

Environmental variations in phenotype are known as acquired characteristics. They’re characteristics that organisms get during their lifetimes

39
Q

What are mutations?

A

Changes to the base sequence of DNA

40
Q

What is the effect of mutations?

A

When mutations occur within a gene, they result in an allele or different version of the gene. Sometimes they have a small effect on the phenotype. New combinations of alleles may also interact with each other to produce new phenotypes

41
Q

What is the human genome project?

A

The human genome project, was a project that hoped to find every single human gene. It started in 1990 and by 2003, 20500 genes were mapped. The project has helped to identify about 1800 genes related to disease which has huge potential benefits for medicine

42
Q

How does the human genome project have potential applications of within medicine - prediction and prevention of diseases?

A

Many common diseases like cancers and heart diseases are caused by the interaction of different genes, as well as lifestyle factors.

  • if doctors knew what genes predisposed people to what diseases we could get individually tailored advice of the best diet and lifestyle to avoid problems
  • docs could check us regularly to ensure early treatment if we do develop the diseases we’re susceptible to
43
Q

How does the human genome project have potential applications of within medicine - testing and treatment for inherited disorders?

A

Inherited disorders are caused by the presence of one or more faulty alleles in a person’s genome

  • scientists are now able to identify the genes and alleles that are suspected of causing an inherited disorder much quicker
  • people can be tested for a disorder and it may be possible to develop better treatments/cures
44
Q

How does the human genome project have potential applications of within medicine - new and better medicines?

A

This research has highlighted some common genetic variations between people. These variations can affect how our individual bodies will react to certain diseases and to the possible treatments

  • scientists can use this knowledge to design new drugs that are specifically tailored to people with a particular gents variation
  • can determine how well an existing drug will work
  • whether disease will respond to drugs
  • enables us to know how a disease affects us on a molecular level - potentially more effective treatments with fewer side effects
45
Q

What are the drawbacks of the human genome project?

A
  • increased stress, if someone knew from an early age they’re susceptible to a disease, they may panic often
  • gene-ism, people with genetic problems come under pressure not to have children
  • discrimination by employers and insurers, people who potentially risk getting a disease may be treated unfairly
46
Q

What do mutation cause in a population of specials?

A

There is usually extensive genetic variation within a population of a species and that these arise through mutations

‼️Biology‼️ (5 decks)

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