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Year 12 EA content > Topic 1: DNA, Genes, The Continuity of Life > Flashcards

Topic 1: DNA, Genes, The Continuity of Life Flashcards

1
Q

define organelle

A

a membrane bound compartment in a cell that performs a specialised function

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2
Q

name the general features of prokaryotes

A
  • lack distinct nucleus
  • no membrane-enclosed organelles
  • contain free floating ribosomes
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3
Q

name the general features of eukaryotes

A

-distinct nucleus
- contain membrane-bound organelles
- contain ribosomes

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4
Q

describe DNA in prokaryotes

A

a single circular chromosomes and plasmids

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5
Q

define intron

A

a segment of DNA or RNA molecule that doesn’t code for proteins and interrupts the sequence of genes

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6
Q

where is DNA found in prokaryotes

A

found in the nucleoid region

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7
Q

where is DNA found in eukaryotes

A

found in the nucleus

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8
Q

define mitochondria

A

organelle in both eukaryotic cells (heterotrophs and autotrophs), site of cellular respiration

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9
Q

explain mitochondrial DNA (mDNA)

A

a double stranded, circular molecule with no introns

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10
Q

recall the basic structure of DNA

A
  • carried hereditary info
  • a double helix structure with two complementary strands
  • nucleotides are the building blocks of DNA/RNA
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11
Q

what are nucleotides

A

a group of molecules that, when linked together, form the building blocks of DNA/RNA

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12
Q

what are nucleotides made of

A

a deoxyribose sugar, a phosphate group, a nitrogenous base

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13
Q

what are the 4 dif types of nitrogenous bases in nucleotides

A

Adenine and Thymine
Guanine and Cytosine
(Thymine is only found in DNA, in RNA it is replaced by Uricil)

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14
Q

whats the dif between maternal and paternal

A

maternal - from mother
paternal - from father

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15
Q

define diploid

A

cell containing 2 complete sets of chromosomes - one from each parent

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16
Q

define haploid

A

cell having a single set of unpaired chromosomes, usually a gamete (sex cell)

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17
Q

what are homologous chromosomes

A
  • have one paternal and one maternal, containing the same genes (the sex genes)
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18
Q

define autosomal chromosomes

A

chroms. not related to gender/ sex (chromosomes 1 to 22)

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19
Q

what are the differences between make and female when it comes to chromosomes 23

A
  • females have two homologous pairs of X chromosomes
  • males have one X and a shorter Y chromosomes
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20
Q

what is a human karyotype

A

an individual’s complete set of chromosomes

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21
Q

define gene

A

segment of DNA that codes for a specific phenotypic trait

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22
Q

define allele

A

the different variations of a gene

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23
Q

define gene locus

A

a fixed positions on a chromosomes where a specific gene is found (location)

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24
Q

homozygous?

A

same alleles (AA)

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25
Q

heterozygous

A

different alleles (Aa)

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26
Q

are all homologous chromosomes the same

A

they contain the same genes, however they are not identical due to the variations between alleles

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27
Q

explain meiosis

A

cell division that results in 4 genetically unique daughter cells - which have half the number of chromosomes (haploid) of the parent cell (diploid)

28
Q

basic process of cellular division:

A

meiosis i –> go from one parent cell to two daughter cells
- two daughter cells then undergo a new cellular division, resulting in each of those forming two new daughter cells themselves

29
Q

what are spermatogenesis and oogenesis

A

the processes of male and female gamete production (spermatogenesis - sperm)

30
Q

define fertilisation

A

the union of male and female gametes to product a zygote: the first diploid cell of a new organism

31
Q

define genome

A

all the genetic material in the chromosomes of an organism - basically the complete DNA sequences of an organism

32
Q

explain non-coding DNA

A
  • majority of human DNA is non-coding - plays important role in gene activity (determine when and where genes are turned on and off)
33
Q

what are examples of non-coding DNA

A

centromeres, telomeres, introns, etc

34
Q

define amino acid

A

the building blocks of proteins - protein structure is determined by the sequence and folding of these amino acids

35
Q

define transcription

A

process by which complementary copy (mRNA) of a gene (DNA) is made in the nucleus

36
Q

define translation

A

process by which an mRNA sequence is converted into a specific sequence of amino acids (carried by tRNA) in the ribosomes

37
Q

define messenger RNA (mRNA)

A

single stranded nucleic acid - carried protein info from the DNA in a cell’s nucleus to the cell’s cytoplasm

38
Q

define transfer RNA (tRNA)

A

small RNA molecule that transfers specific amino acids to the ribosome during formation of proteins

39
Q

define codon

A

set of three nitrogen bases in mRNA

40
Q

define anticodon

A

complementary set of three nitrogen bases in tRNA

41
Q

where does transcription occur

A

nucleus

42
Q

where does RNA processing occur

A

nucleus

43
Q

where does translation occur

A

ribosomes

44
Q

explain gene expression

A

process by which the info stored in a gene is used to synthesize a functional gene product

45
Q

define enzymes

A

speeds up the reactions by lowering the activation energy required

46
Q

what is gene regulation

A

the process of controlling which genes are expressed by which cells

47
Q

define mutation

A

permanent change in the nucleotide sequence of DNA (essential for evolution)

48
Q

what is a point mutation

A

occurs when a single nucleotide base is changed, inserted or deleted from a sequence

49
Q

a point mutation can cause a frameshift - explain

A

the error in the DNA sequence carried through the transcription and translation process

50
Q

define mutagen

A

a physical, chemical or biological agent that causes mutations

51
Q

explain physical mutagens

A

breaks chemical bonds and damage DNA (e.g. include ionizing radiation (some UV, X-rays))

52
Q

explain biological mutagen

A

cause mutations by inserting their own DNA into the human genome in cell division

53
Q

explain non-disjunction mutations

A

occur when homologous chromosomes or sister chromatids fail to separate properly during cell division –>result: daughter cells have incorrect no. of chromosomes (aneuploidy)

54
Q

explain trisomy

A

type of aneuploidy (an abnormality in the number of chromosomes in a cell) where there are 3 chromosomes instead of the normal two for a particular homologous pair –> trisomy 21 = down syndrome

55
Q

what are somatic cells

A

any cell other than the reproductive cells (e.g. muscle cells)

56
Q

how to inherited mutations alter the variations in genotype of offspring..

A

they introduce new alleles into the gene pool, and therefore increase variation within the genotypes of the population

57
Q

what is a sex linked allele

A

one that is carried on one of the sex chromosomes (most often X - as it contains more genetic info)

58
Q

what is polygenic inheritance

A

refers to phenotypic traits that are determined by two or more genes (e.g. skin, eye colour, height)

59
Q

what is recombinant DNA

A

the result of combining the DNA of two dif. species

60
Q

describe the process of making recombinant DNA

A
  1. a gene is isolated from a target organism
  2. its inserted into a bacterial plasmid, which is then inserted back into the bacteria
  3. the bacteria pop. is grown in a culture where it produces the protein products of the inserted gene
61
Q

what is a plasmid

A

small circular DNA strand found in prokaryotic cells - replicate independently of chromosomes

62
Q

what are restriction enzymes

A

DNA sequences are cut at specific nucleotide sequences called recognition sites - this enzyme moves along the length of the DNA, cutting it each time a recognition site is passed

63
Q

what are DNA ligases

A

responsible for joining DNA (or RNA) fragments together

64
Q

what is DNA sequencing

A
  • process of determining the precise order of nucleotides within a segment of DNA
  • determining the order of adenine, guanine,etc
65
Q

what can DNA profiles be used for

A
  • confirm how closely related individuals are
  • trace inheritance patterns
  • solve crimes
66
Q

what is a polymerase chain reaction (PCR)

A
  • DNA samples are usually quite small
  • so, before they can be analysed, samples must be amplified
  • polymerase enzymes catalyse and expotentially amplify copies of a specific sequence
67
Q

explain gel electrophoresis

A
  • a lab technique used to separate mixtures of DNA based on molecular size

Year 12 EA content (7 decks)

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