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B4-B6 > B5.1 - Inheritance > Flashcards

B5.1 - Inheritance Flashcards

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1
Q

Define a phenotype

A

The appearance of an organism

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2
Q

Define variation

A

The differences within a species

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3
Q

Explain the two types of variation. (2)

A 
Genetic variation (genetic material inherited from parents)
Environmental variation (variation caused by your environment - ie. sunlight, hair length - if you cut it or not)
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4
Q

Are most features caused by a single gene or multiple?

A

Usually multiple genes

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5
Q

What is discontinuous variation?

how to show graphically

A
  • variation that can only result in discrete values (one)
  • ONLY GENETIC
  • ie. blood group, gender, eye colour
  • bar chart
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6
Q

What is continuous variation?

how to show graphically

A
  • variation that can take any value within a range
  • genetic + environmental
  • ie. length of fur, skin colour, leaf surface area
  • histogram (single line)
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7
Q

Define a clone

A

An organism that is genetically identical to its parent

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8
Q

What is asexual reproduction?

A

When a single organism reproduces itself (by mitosis), and produces new daughter cells genetically identical to itself

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9
Q

What is different between the offspring in sexual and asexual reproduction and why?

A

Asexual reproduction has the exact same genetic material as the parent, whereas sexual is not identical to parents as the offspring takes genetic information from both parents

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10
Q

Define gametes

A

Sex cells (ie. sperm cell, egg cell)

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11
Q

What happens during fertilisation?

A

Two gamete fuse together to form a zygote

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12
Q

Advantages/ disadvantages of asexual reproduction?

A

Adv - if parent well adapted, offspring has identical characteristics
- one parent needed (reproduction faster = more offspring)

Dis - adapted to one habitat (may all die out if abiotic factors change)
- lack of variation, one disease can wipe our all

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13
Q

Adv/Dis of sexual reproduction?

A

Adv - variation leads to adaptations (if environment changes, at least one organism can survive + reproduce)

Dis - reproduction needs two parents (slower = less offspring)

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14
Q

What are diploid cells in humans?

how many chromosomes

A

Normal body cells (46 chromosomes)

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15
Q

What are haploid cells in humans?

How many chromosomes

A

Sex cells (ova/sperm cells) - 23

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16
Q

What is formed when two gamete cells join together?

A

Diploid cell or ‘zygote’

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17
Q

What process causes the zygote to divide many times to produce a new organism?

A

Mitosis

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18
Q

Define genome

A

All the genetic material within an organism

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19
Q

How is meiosis used in the body?

A

To produce gametes/ sex cells

20
Q

What kind of cells are present at the start of meiosis and what are present at the end?

A

ONE diploid parent cell at start

FOUR haploid daughter cells at end

21
Q

Where does meiosis occur in females, and males?

And what is produced

A

Females - ovaries (makes ova cells)

Male - testes (sperm cells)

22
Q

.

A

Look at diagram on p155

23
Q

Define alleles

A

Different forms of a gene

24
Q

What’s the different between dominant and recessive alleles?

A

Dominant - will always show up
Rr or RR

Recessive - only show up if there are two of them
only rr

25
Q

Define a genotype

A

Genotype is the genetic makeup of an individual cell or organism that determines or contributes to its phenotype

26
Q

What does the genotype of a dominant homozygous individual look like/ a recessive homozygous/ and a heterozygous

A

GG/ gg/ Gg

27
Q

Give 3 examples of dominant characteristics

Give 3 examples of recessive characteristics

A

DOM - free ear lobes
- brown eyes
- dark, wavy hair

REC - joined ear lobes
- blue eyes
- straight, blonde hair

28
Q

Who figured out the basic laws of inheritance of characteristics?
(And how)

A

Mendel (was a Catholic monk)

Carried out experiments on pea plants

29
Q

In the genetic cross between a man who is heterozygous for the Huntington’s allele and a woman who is homozygous recessive for the Huntington’s allele (h).

State the proportion of

(a) homozygotes dominant offspring
(b) heterozygous offspring
(c) homozygotes recessive offspring

A

(a) 0%
(b) 50%
(c) 50%

30
Q

(A) What does a female’s 23rd pair of chromosomes look like?
(B) what does a male’s 23rd pair of chromosomes look like?

A

(A) XX

(B) XY

31
Q

What ‘thing’ determines the sex of a baby?

A

Whether the sperm cell which fertilises the ova cell contains an X or a Y chromosome on the 23rd place.

As it is a HAPLOID cell (has 23 chromosomes only)

32
Q

What is a mutation?

A

A change in which the sequence of DNA bases is altered (may or may not result in a change to the phenotype)

33
Q

Where do variants arise from in a population?

A

From mutations (change in DNA)

34
Q

Are all mutations harmful?

A

Not all, most will not even affect phenotype.

However the ones that do affect phenotype are usually harmful

35
Q

What happens when a mutation occurs within a gene? (5)

A
  • dna bases change/add/deleted
  • change sequence of bases (mRNA Produced is different)
  • animo acids assembled incorrectly
  • wrong protein forms/ fold incorrectly/ active site does not wok
  • cannot bind to substrate/ catalyse reaction
36
Q

What happens if a mutation occurs within a non-coding region of DNA?

A

By altering one of these regions, a variant (also known as a mutation) in noncoding DNA can turn on a gene and cause a protein to be produced in the wrong place or at the wrong time. Alternatively, a variant can reduce or eliminate the production of an important protein when it is needed

37
Q

What did Mendel discover and how, and when?

A

1) characteristics in plants determined by genes
2) genes passed on from both parents (one unit from each)
3) genes dominant/ recessive

1866

38
Q

What did Miescher discover and when?

A
  • acidic substance in nucleus of cell (DNA)

1869

39
Q

Who discovered that genes are made of DNA?

A

Avery, transferred DNA between bacteria (passed trait to cause disease to offspring)
1944

40
Q

Who first found the helical structure of DNA and when?

A

Wilkins and Franklin (X-rayed DNA crystals)

1952

41
Q

What did Watson and crick do?

A

Published description of DNA (complementary base pairings + double helix)
1953

42
Q

Who is dolly the sheep and why is she special?

A

In 1996, was first cloned animal from adult cell

43
Q

what influences the development of the phenotype of an organism? (2)

A
  • the genome
  • organism’s interaction with the environment
44
Q

how could genetic variants affect the phenotypes in coding DNA (protein)

A
  • mutations affecting protein structure

- affect active site of enzymes

45
Q

how could mutations affect the phenotypes in non-coding DNA?(expression of genes)

A
  • stopping transcription of DNA
46
Q

What is the mnemonic to remember the order of scientists?

A

Mixed martial arts can foster world wide carnage

M endel
M iescher
A very
C hargaff
F rankil 
W ilkins 
W atson 
C rick
47
Q

what did chargaff discover?

A

that DNA contains equal amounts of adenine and thymine

and cytosine and guanine

B4-B6 (8 decks)

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