Genetics Flashcards

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1
Q

Genetic is the study of

A

inheritance

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2
Q

In a woman the sex chromosomes are XX, in the man they are

A

XY

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3
Q

Explain briefly what is meant by a gene?

A

section of DNA that carries the code for the production of a particular protein

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4
Q

Where in the nucleus would you find genes?

A

Chromosomes

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5
Q

What is the significance of the fact that the two allele pairs are located on different chromosome

A

they are Heterozygous

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6
Q

What is meant by non-coding DNA?

A

‘junk DNA’

Doesn’t form proteins

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7
Q

What is a chromosome?

A

structure found in the nucleus of a cell

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8
Q

What is meant by sex linked?

A

traits are controlled by the gene is on the X chromosome

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9
Q

What is meant by the term segregation as used in genetics?

A

Inherited characteristics are controlled by pair of factors these factors separate at gamete formation and only one factor is carried in each gamete

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10
Q

State the Law of independent assortment

A

at gamete formation either member of a pair of factors is equally likely to recombine with either member of another pair of factors

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11
Q

What is meant by DNA profiling?

A

unique pattern of DNA from one person that id compared with the DNA profile of another person

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12
Q

State 2 uses of DNA profiling?

A
  1. Crime

2. Medical

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13
Q

Explain what is meant by dominance

A

a gene which presents the recessive gene from working

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14
Q

Define Genotype

A

Genotype is the genetic make up of an organism

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15
Q

Define phenotype

A

Phenotype is physical make up of an organism

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16
Q

Define an allele

A

Different form of the same gene

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17
Q

Define Recessive

A

a gene that is prevented from working by a dominant gene

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18
Q

Define Homozygous

A

Both of the alleles are the same

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19
Q

A change in the genetic material of an organism is called

A

mutation

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20
Q

What is meant by genetic screening?

A

Testing a person’s DNA for the presence of abnormal or altered DNA

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21
Q

Define Nucleic acid

A

polynucleotide macromolecule

eg: DNA and RNA

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22
Q

What is non nucleic DNA

A

location: mitochondria
role: organelles reproduce without the nucleus

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23
Q

Define Heredity

A

The passing of features from parents to offspring by means of genes

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24
Q

Define species

A

group of similar organisms capable of inter-breeding to produce fertile offspring

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25
Q

What is non-coding DNA?

A

DNA that doesn’t code for a protein is also known as ‘Junk DNA’

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26
Q

Define a codon?

A

three bases in sequence it assembles an amino acid during protein synthesis

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27
Q

What is Gene expression?

A

Way in which the genetic code in a gene is decoded and used to make a protein

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28
Q

What is a gene

A

collection of codons, it contains the genetic code to form a protein and controls particular characteristics

29
Q

What is meant by genetic screening?

A

Test to establish the presence or absence of a gene or altered gene

30
Q

Give a brief outline of genetic screening

A
  1. Radioactive section of DNA is added to a DNA sample with a gene of the person being tested
  2. DNA probe only attaches to a normal gene
  3. If the DNA probe doesn’t attach the gene is altered
31
Q

Name the scientists that described the structure of DNA

A

Watson and Crick

32
Q

What does DNA stand for

A

Deoxyribonucleic acid

33
Q

What is the shape of the DNA

A

Double helix

34
Q

What does nucleotide consist of

A

1) phosphate group
2) deoxyribose sugar
3) base

35
Q

What are the four different bases that exist?

A

1) Adenine
2) Guanine
3) Thymine
4) Cytosine

36
Q

Which bonds are between complementary base pairs?

A

Hydrogen bonds

37
Q

How many Hydrogen bonds are present between

  1. adenine and thymine
  2. guanine and cytosine?
A
  1. 2 hydrogen bonds

2. 3 hydrogen bonds

38
Q

How can DNA be stable

A

an enormous number of hydrogen bonds

39
Q

What are bases adenine and guanine classified as

A

Purines

40
Q

What are bases thymine and cytosine called

A

Pyrimidines

41
Q

In DNA, nitrogenous bases occur in complementary pairs. Explain the term complementary as used here

A

Each base has a corresponding matching base

42
Q

What is the function of DNA

A
  1. Heredity material (passes genetic info from parents to offspring in the form of genes)
  2. Human chromosomes are composed of DNA and Protein
  3. Syllabus statement (each chromosome carries a series of genes in linear order along its length)
43
Q

Briefly describe the nature of the genetic code

A
  1. codon is 3 bases in a sequence
  2. each codon codes for one amino acid
  3. gene consists of a collection of codons who code for one protein
  4. the codon sequence determines the amino acid sequence in a protein
  5. mRNA copies the genetic code from DNA and brings it to the ribosome in the cytoplasm where protein synthesis occurs
44
Q

Define DNA replication

A

DNA makes exact copies of itself

45
Q

List 2 stages of DNA replication

A
  1. Opening of the DNA double-helix

2. The synthesis of complementary nucleic acid strands alongside the existing strands to form 2 identical helices

46
Q

Give an account for DNA replication

A
  1. occurs in interphase (part of cell division which involves making an exact copy of DNA)
  2. Hydrogen bonds break down
  3. Two strands separate
  4. DNA acts as a strand to form a new complementary strand
  5. DNA Nucleotides from the cytoplasm move to the nucleus and match up with their corresponding nucleotide on the exposed DNA strands
  6. 2 exact copies of DNA are made called helices
  7. Each new double-strand rewinds to form a double helix
  8. Each DNA molecule is half new and half old and identical
  9. This process requires energy from ATP and Anabolic enzyme DNA polymerase is a catalyst for assembly of DNA nucleotides
47
Q

What does RNA stand for?

A

Ribonucleic Acid

48
Q

What are the similarities in DNA and RNA

A
  1. Both have nucleic acids

2. Both contain bases adenine, guanine and cytosine

49
Q

How does DNA differ from RNA?

A
1. DNA- double-strand
   sugar
   Base=thymine
   Location=nucleus
2. RNA- single strand
    ribose
    Base=Uracil
    Location=Nucleus and cytoplasm
50
Q

Name the 3 types of RNA and give a brief account for each

A
  1. Ribosomal RNA (rRNA)
    • forms ribosomes
    • holds mRNA in place during protein synthesis
  2. Messenger RNA (mRNA)
    • transcribes the genetic code from DNA
    • carries the code to the ribosome
  3. Transfer RNA (tRNA)
    • transfers amino acids to mRNA
    • tRNA attaches to its complementary mRNA placing its amino acid in the correct sequence within its own protein
    • each amino acid has its own tRNA
    • anticodon is complementary to mRNA codon
51
Q

Each mRNA codon specifies one of three possible outcomes during protein synthesis. Name these three possible outcomes

A
  1. Start codon
  2. Codon which assembles an amino acid
  3. Stop codon
52
Q

How are 2 strands of DNA joined together?

A

Hydrogen Bonds

53
Q

What us junk DNA

A

non-coding DNA

54
Q

What was the first procedure that you followed when isolating DNA from plant tissue?

A
  1. Chop onion into pieces
55
Q

What was the reason for that procedure?

A

To disrupt the structure and allow cytoplasm to leak out

56
Q

Washing up liquid is used in the isolation. Give a reason for its use

A

It breaks down membranes

57
Q

Salt is also used in the isolation. explain why

A

to clump the DNA

58
Q

What is a protease?

A

An enzyme that breaks down protein

59
Q

Why is a protease necessary when isolating DNA

A

DNA combines with protein in a chromosome

60
Q

The final stage of the isolation involves the use of frozen-cold ethanol

  1. Describe how it used
  2. For what purpose is it used?
A
  1. Add slowly down the side of the test tube

2. To bring DNA out of the solution

61
Q

What plant did you use when isolating DNA

A

Onion

62
Q

It is usual to chop the tissue and place it in a blender. Suggest a reason for this

A

Chopping- releases the cytoplasm

Blending- Breaks down the cell walls

63
Q

For how long should the blender be allowed to run?

A

3 seconds

64
Q

Washing up liquid is normally used in this experiment. What is its function

A

It breaks down the membrane

65
Q

Salt is also used in this experiment to suggest why

A

to clump the DNA

66
Q

The final separation of the DNA involves the use of alcohol. Under what condition is the alcohol used?

A

Ice-cold

67
Q

Which base can link only to Thymine?

A

Adenine

68
Q

Which base can link only to Cytosine?

A

Guanine