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
What are the processes involved in the formation of a new individual?
1. Meiosis 2. fertilisation 3. mitosis
26
why do sex cells have half the no. of chromosomes of (somatic) body cells
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
factors that increase rate of mutations?
- high energy radiation (UV, x-rays, gamma rays) - carcinogenic chemicals - extreme heat
28
causes of mutation
- errors in DNA replication - errors in cell division - damage by physical/chemical factors
29
how mutation can occur
1. point mutation 2. frame shift 3. parts or whole chromosome involved
30
What is mutation
changes to the DNA sequence or chromosome no. | - new phenotypes can only appear in population after mutation event
31
what are the 2 types of mutation
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
what are the genotypes of symbols X^H, X^h, Y
X^HY, X^hY, X^HX^H, X^HX^h, X^hX^h