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Biology (Year 10) > 4. Genetics > Flashcards

4. Genetics Flashcards

1
Q

What are genetics and characteristics?

A

Genetics are a unit of hereditary characteristics, which are fixed from the moment of fertilisation. However acquired characteristics occur later (ie scars and skills)

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2
Q

What is variation in characteristics?

A

Continuous variation is when there are many intermediate forms between two extremes (ie. height)

Discontinuous variation are characteristics that show few or no intermediate forms (ie tongue rolling)

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3
Q

What is mitosis and what is its function?

A

Mitosis is the process of cellular asexual reproduction, in which the nucleus divides to form two new nuclei.

Three reasons cells reproduce by asexual reproduction is for;

  • growth
  • repair
  • replacement
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4
Q

What is interphase?

A

Interphase occurs before mitosis in preparation for the mitosis cycle. The cellular organelles double, the DNA replicates and protein synthesis occurs

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5
Q

What are the phases in the Mitosis Cycle?

A
  1. Prophase - chromatin (DNA + proteins) in the nucleus condense
  2. Metaphase - the chromosomes gather in the middle of the cell, ready to divide
  3. Anaphase - the chromatids of each chromosome separate and are pulled towards the poles
  4. Telophase - small nuclear vesicles in the cell begin to reform around the groups of chromosomes at each end
  5. Cytokinesis - the cytoplasm divides and daughter cells form
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6
Q

What are the main differences between mitosis and meiosis?

A
  • mitosis produces genetically identical cells, while meiosis produces unique cells
  • mitosis produces diploid cells, meiosis produces haploid cells
  • mitosis occurs throughout an organism’s life, but meiosis only occurs at certain times
  • mitosis is involved in asexual reproduction, meiosis is involved with sexual reproduction
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7
Q

What is meiosis?

A

The formation of gametes through sexual reproduction. Sex cells have 23 chromosomes each (haploid number), arranged into 23 homologous pairs

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8
Q

Provide definitions for the following terms;

  • loci
  • alleles
A
  • the position of a gene on a chromosome
  • different expressions of the same gene

Genes that occupy the same locus of homologous chromosomes are alleles of each other

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9
Q

What are genes?

A

Genes code for the biological development and growth of organisms. Genes are made up of deoxyribonucleic acid (DNA).

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10
Q

What is DNA? What is it made up of?

A

Deoxyribonucleic acid, a long thread-like molecule that contains the genetic instructions for an organisms development.

DNA consists of a sugar phosphate backbone made up of deoxyribose sugar and phosphates. Connected to the deoxyribose sugar are nitrogenous bases. A nucleotide is made up from once sugar, one phosphate and one base.

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11
Q

What is the pairing rule?

A

Only certain nitrogenous bases can pair with each other, purines can only bind with pyrimidine

Adenine (purine) is opposite Thymine (pyrimidine)
Guanine (purine) is opposite Cytosine (pyrimidine)

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12
Q

What is a codon?

A

A codon is a group of three chemical bases that form the DNA. In the arrangement of these bases is the instructions for an amino acid, and a protein from that amino acid

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13
Q

What are introns and exons?

A

Introns separate the coding and ‘non-coding’ DNA in eukaryotic DNA.

Exons code for protein, and thus determine an organism’s traits

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14
Q

What is the process of transcription?

A

The process in which DNA codes for messenger RNA. Initially, the whole gene is turned into mRNA, including the introns, which is called pre mRNA.

Next the introns are removed in a process called splicing, where the exons then join together to form the processed mRNA. This molecule than codes for proteins through the translation process.

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15
Q

How do scientists determine the coding sections of DNA?

A

Scientists work backwards from proteins to identify the mRNA that codes for it. Once they determine the mRNA sequence, they can make complementary DNA which is made up of exons. They then compare this to the DNA to find the matching gene

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16
Q

What is non-coding DNA?

A

Although scientists do not yet know the function of non-coding DNA, it significantly differs between individuals (ie fingerprinting)

Some of the non-coding DNA can be transcribed however, such as introns and functional RNA which contributes to protein synthesis

17
Q

What is a mutation?

A

The change in genetic material of an organism, usually in the DNA

A permanent change in the genetic code of a cell

18
Q

How do you know if a mutation can be passed onto offspring?

A

If a mutation occurs in the gamete, it can be passed onto the offspring of the affected individual. It it occurs in somatic cells (body cells), it cannot be inherited

19
Q

What is the difference between spontaneous and induced mutations?

A

Induced mutations are caused by environmental factors (ie radiation), whereas spontaneous mutation are the result of random mistakes in DNA replication

20
Q

What’s the difference between positive, negative and neutral mutations?

A

Positive mutations: causes a change that is beneficial

Neutral mutations: has no impact on the phenotype

Negative mutations: changes that endanger the organisms survival

21
Q

What are block mutations?

A

Mutations where parts of the chromosomes are deleted, repeated or translocated to other chromosomes, which impacts the alleles

22
Q

What are these mutations?

  • when one chromosome is present in an abnormal number of copes
  • when the chromosome number doubles
A
  • aneuploidy (eg Down Syndrome)

- Polypoids

23
Q

What are the 4 types of chromosomal structural changes?

A
  • deletion: part of a chromosome or DNA sequence is left out during DNA replication
  • inversion: a segment of a chromosome is reversed end to end
  • translocation: unusual rearrangements of chromosomes
  • duplication: production of one or more chromosomes or DNA pieces
24
Q

What is crossing over?

A

Occurs in prophase 1, when the two chromosomes of a homologous pair exchange equal segments with each other

25
Q

What is the difference between chromosomal and genetic mutations?

A

Chromosomal mutations involve chromosomal structural changes that affect entire chromosomes, whereas genetic mutations involve changes to DNA bases

26
Q

What occurs with a gene mutation?

A

Gene mutations involve changes to a the bases of a DNA molecule. This impacts the codon’s production of specific amino acids, thus affecting the protein for which the gene codes.

27
Q

What are types of gene mutations?

A
  • gene/point mutations: changes to one nucleotide in the DNA sequence
  • substitution: an incorrect nucleotide is substituted for the correct one
  • deletion: a nucleotide is removed from the DNA sequence
  • insertion: one nucleotide is added to the DNA sequence
28
Q

What are possible consequences of a mutation?

A
  • silent mutation: no effect
  • missense mutation: substitution causes a new amino acid to be produced
  • frameshift mutation: insertion or deletion of a new nucleotide ‘frameshifts’ the other codons, resulting in all new amino acids
  • nonsense mutation: causes formation of a stop codon
29
Q

What are mutagens?

A

A physical or chemical environmental factor that can change an individual’s DNA, increasing risk of mutations (eg radiation, chemical compounds)

30
Q

What is the difference between a phenotype and genotype?

A

Phenotype: how the trait physically shows up in the organism (ie black fur, blue eyes)

Genotype: the genes present in an organism’s DNA (represented by letters, eg AA or aa)

31
Q

What is the difference between co-dominance and incomplete dominance in genes?

A

Codominant genes result in mixed phenotype (ie black fur x white fur = black and white fur)

Whereas incomplete dominance between genes results in a completely new phenotype (ie black fur x white fur = yellow fur)

32
Q

What is the impact of multiple alleles in chromosomal pairs?

A

There are different expressions for the same gene, ie brown eyes, blue eyes

33
Q

What is a codon?

A

A codon is a group of three chemical bases that form the DNA. In the arrangement of these bases is the instructions for an amino acid, and a protein from that amino acid

34
Q

What are introns and exons?

A

Introns separate the coding and ‘non-coding’ DNA in eukaryotic DNA.

Exons code for protein, and thus determine an organism’s traits

35
Q

What is the process of transcription?

A

The process in which DNA codes for messenger RNA. Initially, the whole gene is turned into mRNA, including the introns, which is called pre mRNA.

Next the introns are removed in a process called splicing, where the exons then join together to form the processed mRNA. This molecule than codes for proteins through the translation process.

36
Q

How do scientists determine the coding sections of DNA?

A

Scientists work backwards from proteins to identify the mRNA that codes for it. Once they determine the mRNA sequence, they can make complementary DNA which is made up of exons. They then compare this to the DNA to find the matching gene

37
Q

What is non-coding DNA?

A

Although scientists do not yet know the function of non-coding DNA, it significantly differs between individuals (ie fingerprinting)

Some of the non-coding DNA can be transcribed however, such as introns and functional RNA which contributes to protein synthesis

Biology (Year 10) (4 decks)

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