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SCI BIOLOGY Flashcards

1
Q

DNA

A

DNA is a chemical that carries genetic instructions

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2
Q

Chromosome

A

Threadlike structures that contain long lengths of DNA that holds many genes.

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3
Q

Gene

A

Section of a chromosome that codes for one trait e.g. eye colour

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4
Q

Allele

A

The different forms of a gene e.g. blue eyes

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5
Q

Gamete

A

A sex cell with half the number of chromosomes

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6
Q

Fertilisation

A

The fusion of two gametes

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7
Q

Zygote

A

A fertilised egg cell

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8
Q

Embryo

A

A ball of cells formed from the zygote by cell division.

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9
Q

Foetus

A

An unborn or unhatched offspring that has developed beyond an embryo.

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10
Q

Homologous chromosome

A

Homologous Pair of Chromosomes have the same genes in the same loci

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11
Q

Meiosis

A

Meiosis is a cell division process that produces genetically unique gametes with half the number of chromosomes

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12
Q

Mitosis

A

The type of cell division that body cells are made by.

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13
Q

Sexual Reproduction

A

Reproduction that involves two individuals contributing genetically to offspring.

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14
Q

Asexual Reproduction

A

Reproduction that involves one individual contributing genetically to offspring.

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15
Q

Genetic Variation

A

The differences (in DNA) of individuals in a population/species

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16
Q

Continuous Variation

A

Continuous Variation where there is a complete range of measurements from one extreme to another e.g. height, body mass

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17
Q

Discontinuous Variation

A

Where the characteristics fall into discrete categories

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18
Q

Monohybrid inheritance

A

Monohybrid Inheritance is the inheritance of characteristics controlled by a single gene (mono = one).

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19
Q

Genotype

A

The alleles an individual has for a trait

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20
Q

Phenotype

A

The physical expression of the gene

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21
Q

Dominant allele

A

The allele that is always expressed if present

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22
Q

Recessive allele

A

The allele that is only expressed in the homozygous condition

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23
Q

Homozygous

A

Genotype with two of the same alleles

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24
Q

Heterozygous

A

Genotype with one dominant and one recessive allele

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25
Punnett square
A diagram used to determine the probable outcomes of a genetic cross between two individuals.
26
Pure Breeding
An organism that is homozygous for a trait.
27
Natural Selection
The process whereby organisms better adapted to their environment tend to survive and produce more offspring.
28
Mutation
A change in the base sequence of DNA. The only source of new genetic variation
29
Point Mutation
A point mutation occurs when a single base or very few bases is changed which affects only a single gene.
30
Chromosomal Mutation
A chromosomal mutation affects the whole or a part of a chromosome which affects multiple genes.
31
Genetics
The study of the variation and inheritance of genes
32
Selective Breeding
The process of choosing only plants and animals with desirable characteristics to reproduce
33
Inbreeding
The production of offspring from the mating or breeding of individuals or organisms that are closely related genetically
34
Rosalind Franklin
The discovery of the structure of DNA in 1953 was made possible by Dr Rosalind Franklin's X-ray diffraction work. Her creation of the famous Photo 51 deduced the double-helix structure of deoxyribonucleic acid.
35
How is the genetic code read
In triplets, triplets code for amino acids. Amino acids are ordered according to the base sequence to form different proteins.
36
Base Pairing
A - T , G - C
37
Parts of a Nucleotide
deoxyribose sugar, phosphate and base
38
Process of Natural Selection
Over production & variation among offspring, competition, differential survival & reproduction, inheritance of favourable alleles
39
Inbreeding Depression
Due to inbreeding offspring will carry harmful diseases which could affect their lifespan.
40
Types of Point mutations
- Substitution - Insertion - Deletion
41
Types of Chromosomal Mutations
Deletion, duplication, inversion, and translocation
42
Extra chromosome in the 21st pair
Trisomy 21
43
Extra X chromosome
Kleinfelter - Only occurs in men
44
Missing X chromosome
Turner' Syndrome - Only in females
45
Implications in inbreeding Bulldogs
- Severe Breathing Issues - Skin problems - Joint problems - Dental Issues
46
Implications in inbreeding King Charles Spaniels
Syringomyelia: - Inability to move neck without pain or discomfort - Yelping - Crying - Developing a wobble when they walk
47
Haemophilia
An inherited bleeding disorder in which the blood does not clot properly.
48
How is Haemophilia Caused
Caused by a point mutation. Located on the X chromosome
49
What can Haemophilia lead to
This can lead to spontaneously bleeding as will as bleeding following injuries or surgery
50
Cystic fibroses
A inherited disorder that causes severe damage to the lungs, digestive system and other organs in the body.
51
How is Cystic fibroses Caused
Cystic fibrosis can be caused by a deletion point mutation of three bases in the CFTR gene which is recessive.
52
What can Cystic fibroses lead to
The mucus, sweat and digestive juices become sticky and thick. These plug up tubes, ducts and passageways. This causes a higher rate of lung infection and lower nutrition absorption
53
Sickle Cell Anaemia
An inherited disorder. Some red blood cells are shaped like sickles or crescent moons. These sickle cells also become rigid and sticky, which can slow or block blood flow.
54
What can Sickle Cell Anaemia lead to
This can lead to problems such as clots, joint pain and anaemia. The lack of oxygen may cause heart and liver damage, and even death.
55
How is Sickle Cell Anaemia Caused
Caused by a substitution point mutation.
56
Recombination / Crossing over
Homologous chromosomes can swap small pieces of their chromatids when they are lines up.
57
Independent Assortment
Happens when the chromosomes line up in their homologous pairs. A random alignment of homologous chromosomes
58
Number of chromosomes in human cells
23 pairs, 46 individual
59
The Genetic Code
The Base Sequence
59
How is variation occurred in sexual reproduction
Shuffles the genetic information of a parent when gametes are produced through meiosis, and it also mixes the genetic information of the two parents through fertilisation. Offspring are produced with differences in their DNA.
60
Why do individuals inherit 2 of each chromosome
They inherit one copy of a chromosomes from each parent. Therefore every person carries two copies of each gene
61
Sister Chromatids
Duplicated chromosomes that are connected to each other at their center points (centromere). Have the same alleles.
62
Somatic Cells
A body cell that has 2 sets of chromosomes
63
How fertilisation produces genetic variation
Fertilisation mixes the DNA of two parents forming a zygote. It is random as to which two gametes from each parent join together. Meaning fertilisation can result in many different combinations of gametes in offspring
64
Test Cross
when an individual showing the dominant phenotype is crossed with an individual showing the recessive phenotype to identify whether the individual is homozygous
65
DNA sequencing
The process of determining the exact order or sequence of bases in a section of DNA or gene.
66
Mutagens
Mutations can be caused by mutagens an example of this is radioactive substances
67
Genetic Screening
The process of sequencing a section of DNA to identify mutations in genes that can cause or increase the risk of a disease such as cancer.
68
What is Stomach cancer caused by
A mutation in the CDH1 gene. Carriers of the mutated gene have a 70% higher chance of developing stomach cancer
69
How is Genetic screening carried out
A blood or saliva sample is collected and the DNA is sequenced. A Normal sequence chromatograms is compared to a sample chromatogram.
70
Treatment options for carriers of the mutated CDH1 gene
Regular checks for cancer or may choose to surgically remove the stomach.
71
Māori rates of stomach cancer compared to Europeans
3x higher than Europeans due to a higher incidence of the CDH1 allele
72
How DNA sequencing is used in the genetic screening for cystic fibrosis
Individuals with a family member with Cystic Fibrosis and their partner may choose to have their DNA sequenced to see if they are carriers of the mutated CFTR gene before having children.
73
Treatment options are available if someone is identified as a carrier of the mutated CFTR gene?
If both parents are identified as carriers of the mutated gene, they can undergo genetic counselling to decide whether or not to have biological children.
74
Female cancer chances
Female carriers a 30-40% higher risk of developing breast cancer.

Science (9 decks)

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