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Science 2020 > Inheritance > Flashcards

Inheritance Flashcards

1
Q

What are chromosomes?

A
  • thread-like structure of DNA which carries genetic info of cell
  • found in nucleus of animal cells
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2
Q

What is DNA and its structure?

A
  • molecule that contains the genetic instructions for development + function of organism
  • double helix structure (sugar phosphate backbone with base pairs AT, GC linked by hydrogen bonds)
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3
Q

What is a gene?

A

A section of DNA (group of base pairs) that codes for formation of a protein controlling specific characteristic of an organism

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4
Q

What is an allele?

A

different versions of the same gene

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5
Q

How is sex inherited/determined by genes?

A
  • 1 pair of chromosomes (sex ones) determines sex

- The pair can either be XX for female and XY for male

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6
Q

What is the difference between haploid and diploid?

A
  • haploid cells contain one set of unpaired chromosomes

- diploid cells contain 2 sets of chromosomes with each type having a pair

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7
Q

How many chromosomes do somatic body cells and sex cells have?

A
  • BODY CELLS = 46 chromosomes, 23 pairs
    (22 pairs autosomal chromosomes, 1 pair sex chromosome XX, XY)
  • sex cells = 23 chromosomes
    (22 autosomal chromosome, 1 sex chromosome X or Y_
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8
Q

What is mitosis?

A

cell division that produces 2 genetically identical daughter cells (each 2n)
- used for growth, reproduction of cell

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9
Q

What is meiosis?

A

cell division producing 4 daughter cells (each n)

- PRODUCES SEX CELLS (gametes)

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10
Q

What are the names of the bases and their pairings?

A

Adenine - Thymine

Guanine - Cytosine

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11
Q

What are dominant and recessive alleles?

A
  • Dominant gene always shown in phenotype
  • recessive is still existent but masked by dominant
    (only shown in recessive homozyg. tt)
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12
Q

what is the genotype and phenotype?

A

Genotype = genetic makeup of organism (ie. TT, Tt, tt)

Phenotype = visible characteristics of organism

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13
Q

What do family pedigrees show?

A

the inheritance of an allele over generations

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14
Q

What is co-dominance?

A
  • when 2 heterozygous alleles are expressed (ie. blood type A + blood type B = blood type AB)
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15
Q

What is incomplete dominance?

A
  • blending of parent alleles that results in a third phenotype that doesn’t look like either of parents
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16
Q

What is a sex-linked characteristic?

A
  • A characteristic where the gene responsible is located on a sex chromosome
  • THEREFORE it is more common in one sex than another (ie. female carriers of colour blindness)
17
Q

What is a mutation?

A
  • changes to the DNA sequence or chromosome number

- new phenotypes can ONLY appear in a population after a mutation event

18
Q

What is a mutation?

HOW DOES IT OCCUR AND WORK?!

A
  • changes to the DNA sequence or chromosome number

- new phenotypes can ONLY appear in a population after a mutation event

19
Q

What are the types of mutation?

A
  1. point mutation
  2. frame shift
  3. parts or whole chromosome involved
20
Q

What can cause mutation in genes and chromosomes?

A
  1. errors in DNA replication
  2. errors in cell division
  3. damage by physical or chemical factors
21
Q

What are the 3 modes of inheritance?

A
  1. Autosomal dominant/recessive
  2. Sex linked (X linked) dominant recessive
  3. Incomplete dominane
22
Q

Why does sex linked inheritance occur?

A

traits are more common to one gender as the missing arm on Y chromosome means for some trait, only one allele (X) is present and can contribute to phenotype

23
Q

why can only females be carriers and only men be affected & possess the trait?

A
  • men do not have another allele to dominate over defective allele
  • female has another allele inherited from other parent (normal + dom.) but can carry the trait as it is recessive and still existent but masked
24
Q

what is fertilisation?

A

union of female and male gametes (sperm + egg) to produce a zygote

25
Q

What are the processes involved in the formation of a new individual?

A
  1. Meiosis
  2. fertilisation
  3. mitosis
26
Q

why do sex cells have half the no. of chromosomes of (somatic) body cells

A

to maintain the fixed no. of chromosomes in a species, gametes need to have half the no. of chromosomes of a somatic cell

(restored in fertilisation when the gametes fuse to produce zygote)

27
Q

factors that increase rate of mutations?

A
  • high energy radiation (UV, x-rays, gamma rays)
  • carcinogenic chemicals
  • extreme heat
28
Q

causes of mutation

A
  • errors in DNA replication
  • errors in cell division
  • damage by physical/chemical factors
29
Q

how mutation can occur

A
  1. point mutation
  2. frame shift
  3. parts or whole chromosome involved
30
Q

What is mutation

A

changes to the DNA sequence or chromosome no.

- new phenotypes can only appear in population after mutation event

31
Q

what are the 2 types of mutation

A
  1. gene mutation: change in the DNA sequence of gene (eg. sickle cell anaemia)
  2. chromosomal mutation: change in the no. of chromosomes (eg. Down’s syndrome)
32
Q

what are the genotypes of symbols X^H, X^h, Y

A

X^HY, X^hY, X^HX^H, X^HX^h, X^hX^h

Science 2020 (5 decks)

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