Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HCHS GCSE Science 3 - Biology > Section 3 - Genetics > Flashcards

Section 3 - Genetics Flashcards

You may prefer our related Brainscape-certified flashcards:
GCSE Religious Studies - Edexcel Route A flashcards GCSE Religious Studies - Eduqas Route A flashcards AP® Biology flashcards GCSE Geography - AQA flashcards Biology 101 flashcards GCSE Religious Studies - Edexcel Route B flashcards GCSE Religious Studies - Eduqas Route B flashcards
1
Q

What is sexual reproduction?

A

The process where genetic information from two organisms (the mother and father) is combined to produce offspring who are genetically different from both parents.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are gametes?

A

Cells used in sexual reproduction that have a haploid nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does it mean if a cell has a haploid nucleus?

A

The nucleus has half the number of chromosomes of normal cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many chromosomes do humans have?

A

46.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does it mean if a cell has a diploid nucleus?

A

the nucleus has the full number of chromosomes of normal cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the gametes in animals?

A

Sperm cells and egg cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a zygote?

A

A cell made when a male gamete and a female gamete fuse in fertilisation, it has a diploid nucleus with genetic information from both parents.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is meiosis?

A

A type of cell division that forms gametes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the process of meiosis.

A

Before the first division, the cell duplicates its DNA to form X-shaped chromosomes with genetically identical arms.
The chromosomes line up in pairs in the centre of the cell.
The pairs are then pulled apart so each new cell will only have one copy of each chromosome. This means that each cell will have a unique mix of the mother and father’s DNA
The cells divide fully.
The chromosomes line up single file down the cell’s centre.
The arms of the chromosomes are then pulled apart.
The cells split, leaving four haploid daughter cells- these are the gametes. The gametes are all genetically different.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is asexual reproduction?

A

The process where an organism produces an offspring which is genetically identical to itself through mitosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the advantages and disadvantages of asexual reproduction?

A

Asexual reproduction can produce many offspring very quickly, this can allow organisms to colonise areas very quickly.
Only one parent is needed, which allows organisms to reproduce in favourable conditions without having to wait for a mate.
However, the lack of genetic variation between offspring can leave the entire population of the organism susceptible to changes in the environment, like disease or weather, because none of the offspring are resistant to the change.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the advantages and disadvantages of sexual reproduction?

A

Sexual reproduction creates genetic variation within the population, which allows the population to survive changes in the environment as some individuals are likely to have developed characteristics to withstand the changes. This leads to natural selection and evolution.
However, sexual reproduction takes more time, because of meiosis and finding a mate, so fewer offspring are produced over an organism’s lifetime.
Two parents are needed which can cause problems if individuals are isolated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is DNA?

A

A complex polymer made from a chain of monomers called nucleotides, it has two strands wrapped together in a double helix structure, and it contains the instructions for an organism’s characteristics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a nucleotide?

A

A naturally occurring monomer that forms DNA, made of a phosphate molecule, a sugar molecule and one of four different base molecules. The phosphate and sugar molecules alternate and a base is bonded to each sugar molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the four base molecules found in DNA?

A

Adenine, thymine, cytosine and guanine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are complementary base pairs? What holds them together?

A

The base molecules in DNA which always pair up, the two pairs are adenine with thymine and cytosine with guanine. They are held together with weak hydrogen bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are chromosomes?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a gene?

A

A section of DNA found on a chromosome that contains the code of a particular protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a genome?

A

An organisms complete set of DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the process of extracting DNA from fruit cells.

A

Mash some strawberries, or another fruit, and mix them into a beaker containing a solution of salt and detergent.
Filter the mixture to remove the froth and the large, insoluble bits of cell.
Gently add some ice-cold alcohol to the filtered mixture.
The DNA will come out of solution as a stringy white precipitate that can be carefully fished out with a glass rod.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is detergent used when extracting DNA from fruit cells?

A

The detergent breaks down the cell membranes to release the DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why is salt used when extracting DNA from fruit cells?

A

The salt causes the DNA to stick together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe how DNA is used in protein synthesis.

A

Each different protein has a specific number and order of amino acids.
These chains fold up to give each protein a different, specific shape- giving it a specific function. Which is why enzymes have specifically shaped active sites, to only catalyse certain reactions.
Each gene contains the order and number of amino acids for the protein it codes for through the order of bases in that gene.
The amino acids are joined together in the order coded in the gene to make the necessary protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are non-coding regions?

A

Regions of DNA that do not code for any amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is a mutation?

A

A rare, random change to an organism’s DNA base sequence that can be inherited.

26
Q

What are the stages of protein synthesis?

A

Transcription and translation.

27
Q

What is a base triplet?

A

A group of three consecutive bases in a gene that code for a specific amino acid.

28
Q

What occurs in the transcription stage of protein synthesis?

A

RNA polymerase binds to a region of non-coding DNA in front of a gene.
The two DNA strands unzip and the RNA polymerase moves along one of the strands.
The RNA polymerase uses the coding DNA in the gene as a template to make mRNA.
The mRNA then moves out of the nucleus and joins with a ribosome.

29
Q

What ensures that the mRNA produced from transcription is complementary to the gene?

A

Base pairing between the DNA and RNA means the RNA is correctly transcribed.

30
Q

What is RNA?

A

A polymer made of nucleotides.

31
Q

What are the differences between DNA and RNA?

A

RNA is normally shorter than DNA, it only has one strand and uses the base uracil instead of thymine.

32
Q

What occurs in the translation stage of protein synthesis?

A

Amino acids are brought to the ribosome by tRNA molecules.
The order in which the amino acids are brought to the ribosome matches the order of base triplets in the mRNA, also known as codons.
Part of the tRNA’s structure is called the anticodon, and it fixes to the codon for the amino acid it is connected to.
The ribosome joins the amino acids together, making a polypeptide (protein).

33
Q

What ensures the amino acids are in the right order during translation?

A

The anticodon of the tRNA that it is connected to is complementary to the codon of the RNA for its specific amino acid, so they couldn’t be arranged in the wrong order.

34
Q

What is mRNA

A

Messenger RNA, it takes information from the gene to the ribosome to make a specific protein.

35
Q

What is tRNA?

A

Transfer RNA, it carries the amino acids to the ribosome and attaches to specific points of mRNA molecules depending on their anticodon.

36
Q

What is an anticodon?

A

A base triplet found on tRNA molecules.

37
Q

How is non-coding DNA used in protein synthesis?

A

RNA polymerase binds to it in order to start transcription.

How easy it is for the RNA polymerase to bind to the non-coding region effects how much of the protein is made.

38
Q

How would a mutation in a coding region of DNA affect an organism’s phenotype?

A

It would change the protein being formed by the cell because one of the amino acids in the protein would be changed to a different one, which may affect the protein’s function.

39
Q

How would a mutation in a non-coding region of DNA affect an organism’s phenotype?

A

It would make it easier or harder for the DNA polymerase to attach to the DNA, which would affect how much of the protein was produced.

40
Q

What is a phenotype?

A

the set of physical characteristics inherited from an organism’s parents.

41
Q

Who was Gregor Mendel and what did he do?

A

He was an Austrian monk in the mid 19th century, His experiments on how characteristics in plants were passed from one generation to the next eventually became the foundation of modern genetics after they were published in 1866.

42
Q

How did Mendel use pea plants to investigate plant height? What were his findings?

A

He crossed two pea plants of different heights- one tall, one short. The offspring were all tall pea plants.
He then crossed two of the offspring and found for every three tall plants produced there would be one short offspring.
He concluded that pea plant height was determined by separately inherited “hereditary units” passed on from the parents and that the unit for tall, T, was dominant over the unit for short, t.

43
Q

What were Mendel’s three important conclusions about the characteristics of plants?

A

Characteristics were determined by “hereditary units”
These units were passed on to offspring from both parents, one from each parent.
These units can be dominant or recessive- if an individual has both the dominant and recessive unit, the dominant characteristic will be displayed.

44
Q

What are Mendel’s hereditary units now known as?

A

Genes.

45
Q

What are alleles?

A

Different versions of the same gene.

46
Q

How many alleles do we have for each gene?

A

Two, one from each parent.

47
Q

How are recessive genes displayed of genetic diagrams?

A

With lower case letters.

48
Q

What does it mean if a gene is dominant?

A

Its characteristics will be shown over its allele.

49
Q

How are dominant genes displayed on genetic diagrams?

A

With capital letters.

50
Q

What does it mean if a gene is recessive?

A

Its characteristics will not be shown if its allele is dominant.

51
Q

If an organism displays a recessive characteristic what does that suggest about its genes?

A

It has two recessive alleles.

52
Q

What is a genotype?

A

The combination of alleles an organism has, these determine the organism’s phenotype.

53
Q

What does it mean if an organism has a homozygous genotype?

A

The alleles of a specific trait are the same, so either two dominant or two recessive alleles.

54
Q

What does it mean if an organism has a heterozygous genotype?

A

The alleles of a specific trait are different, one dominant and one recessive.

55
Q

What is a family pedigree?

A

A family tree of genetic disorders.

56
Q

What are sex-linked genetic disorders?

A

Genetic disorders found in the genes of X and Y chromosomes.

57
Q

Why are men more at risk of inheriting sex-linked genetic disorders?

A

The Y chromosome is much shorter than the X chromosome, this means that men often only have one allele for many genes, so they only need one faulty allele, even if it’s recessive whereas women need two faulty alleles, if its recessive.

58
Q

Why is colour blindness more common in men than women?

A

Colour blindness is caused by a faulty allele found on the X chromosome, and is also recessive, so men only need one copy,whereas women need two.

59
Q

What does it mean if a pair of alleles are codominant?

A

Neither allele is dominant over the other, and the organism will show characteristics from both alleles.

60
Q

What are the four blood types? Which alleles are needed for each type?

A

A, IᴬIᴬ or IᴬIᵒ
B, IᴮIᴮ or IᴮIᵒ
AB, IᴬIᴮ
O, IᵒIᵒ

HCHS GCSE Science 3 - Biology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions