Topic 8 Inheritance, Variation And Evolution Flashcards
1
Q
What does each gene code for?
A
Particular sequence of amino acids to make specific protein
2
Q
What is the genome?
A
Entire genetic material of organism
3
Q
What are 3 reasons understanding the human genome is important?
A
1) Search for genes linked to different types of disease
2) understanding and treatment of inherited disorders
3) tracing human migration patterns from past
4
Q
Describe the structure of DNA?
A
Polymer made from 4 different nucleotides
5
Q
What does each nucleotide consist of (3 things)?
A
Sugar, phosphate group, base
6
Q
What is complementary base pairing?
A
A always pairs with T, C always pairs with G
7
Q
What is each amino acid coded for by?
A
Sequence of 3 bases in gene
8
Q
What does the order of bases control?
A
Order amino acids assembled to produce particular protein
9
Q
What do long strands of DNA consist of?
A
Alternating sugar and phosphate sections, attached to each sugar is 1 of 4 bases
10
Q
What can non-coding parts of DNA do?
A
Switch genes on and off, control whether or not gene is expressed
11
Q
What happens when a protein chain is complete?
A
Folds up to form unique shape, enables proteins to do their job
12
Q
What are 3 types/examples of proteins?
A
Enzymes
Hormones
Structural proteins (collagen)
13
Q
What are proteins synthesised on?
A
Ribosomes
14
Q
What effects do most mutations have on the protein?
A
None/slightly but appearance or function not changed
15
Q
How do mutations occur?
A
Continuously
16
Q
What do a few mutations code for?
A
Altered protein with different shape (enzymes/structural proteins)
17
Q
What do mutations change in DNA?
A
Sequence of DNA bases in gene, produces genetic variant
18
Q
What can a mutation in non-coding DNA alter?
A
How genes expressed
19
Q
What does sexual reproduction involve in flowering plants?
A
Pollen and egg cells
20
Q
How are gametes produced?
A
By meiosis
21
Q
Where does meiosis occur in humans?
A
Reproductive organs
22
Q
Want are the 3 stages of meiosis?
A
Genetic info copied
Cell divides twice to form 4 gametes, each with single set of chromosomes
All gametes genetically different
23
Q
What happens after gametes join at fertilisation?
A
New cell divides by mitosis to produce lots of new cells in embryo, as embryo develops cells differentiate
24
Q
What are 3 advantages of sexual reproduction?
A
Produces variation in offspring
If environment changes, variation gives survival advantage by natural selection
Natural selection can be speeded up by humans in selective breeding to increase food production
25
What are **4 advantages of asexual reproduction**?
Only **one parent** needed
**More time and energy efficient** (do need to find mate)
**Faster than sexual reproduction**
**Many identical offspring can be produced in favourable conditions**
26
What are **3 organisms** that **reproduce both sexually and asexually**?
**Malarial parasites**
**Fungi**
**Plants**
27
How can **malarial parasites reproduce both ways**?
**Asexually in human host** but **sexually in mosquito**
28
How can **fungi reproduce both ways**?
**Asexually by spores** but also **sexually to give variation**
29
What are **2 ways plants can reproduce asexually**?
Runners
Bulb division
30
What are **2 inherited disorders**?
**Cystic fibrosis - genetic disorder of cell membranes**
**Polydactyl - extra fingers/toes**
31
What **type of allele is cystic fibrosis caused by**?
**Recessive**
32
Why **type of allele is polydactyl caused by**?
**Dominant**
33
How can **embryos be screened for genetic disorders**?
In **IVF before implantation, remove cell from each embryo** and **analyse genes**
34
What are **3 arguments against embryonic screening**?
**Implies people with genetic problems are undesirable**
**Everyone may want to screen embryos** to **pick most desirable one**
**Expensive**
35
What are **3 arguments for embryonic screening**?
**Stop suffering**
**Treat disorders cost tax payers money**
**Laws stop it going too far**
36
What is **variation**?
**Differences in characteristics of individuals in a population**
37
What can **mutations very rarely result in**?
**New phenotype in species**
38
What is **selective breeding**?
**Humans artificially select and breed plants and animals for particular genetic characteristics**
39
What are **4 organisms** that are **selectively bred** to **develop features** that are **useful or attractive**?
**Crops with disease resistance**
**Animals** that produce **more meat or milk**
**Domestic dogs with gentle nature**
**Large or unusual flowers**
40
What are the **4 steps in the process of selective breeding**?
1) **choose parents with desired characteristics** from mixed population
2) **breed together**
3) **select best offspring** and **breed together**
4) **continue process over several generations** until **all offspring show desired characteristic**
41
What is the **main drawback of selective breeding**?
Lead to ‘**inbreeding**’, some breeds particularly **prone to a disease** or **inherited defects**
42
What is **genetic engineering**?
**Modifying genome of organism** by **introducing gene from another organism** to give **desired characteristic**
43
What are **2 examples of genetic engineering**?
**Bacterial cells** genetically engineered to **produce human insulin** to **treat diabetes**
**GM crops** to be **resistant to disease, insects, herbicides** or **produce bigger better fruits**
44
Why is the **transfer of a gene** carried out when the organism is at an **early stage of development**?
**Organism develops with desired characteristics**
45
What are the **3 steps in genetic engineering**?
1) **enzymes** used to **isolate required gene**
2) **gene inserted into vector** (usually **bacterial plasmid** or **virus**)
3) **vector** used to **insert gene into required cells**
46
What are **2 cons of GM crops**?
**Effect on populations of wild flowers and insects- reduce farmland biodiversity**
**Effects of eating GM crops on human health not fully explored**
47
What is **modern medical research exploring with genetic engineering**?
**Genetic modification to overcome some inherited disorders**
48
What are **2 pros of GM crops**?
**Increase yields**
Engineered to **contain nutrients missing from diets** in **developing nations**
49
What are **2 methods of cloning plants**?
**Tissue culture**- using **small groups of cells from part of plant** to **grow identical new plants**
**Cuttings- older, simpler method**, produce **many identical plants quickly and cheaply**
50
What is **tissue culture important for**?
**Preserve rare plant species** or by **plant nurseries** to **produce lots of stock quickly**
51
What are **2 methods of animal cloning**?
**Embryo transplants**
**Adult cell cloning**
52
What are the **2 steps in embryo transplants**?
**Splitting apart cells** from **developing animal embryo before become specialised**
**Cloned embryos implanted** into **host mothers**
53
What are the **4 steps in adult cell cloning**?
1) **nucleus removed** from **unfertilised egg cell**
2) **nucleus** from **adult body cell (skin cell) inserted** into **egg cell**
3) **electric shock stimulates egg cell** to **divide** to form **embryo**
4) when **ball of cells, inserted** into **womb of adult female**
54
What is an **example of adult cell cloning**?
**Dolly the cloned sheep**
55
What are **3 risks of cloning**?
**Reduced gene pool**
**Health problems in cloned animals**
**Human cloning in future?**
56
What are **2 benefits of cloning**?
**Study of animal clones -greater understanding of development of embryo**
**Preserve endangered species**
57
What were **3 reasons** why the **theory of evolution by natural selection was only gradually accepted**?
**Challenged idea God made all animals and plants**
**Insufficient evidence at time to convince many scientists**
**Mechanism of inheritance and variation not known** until **50 years after theory published**
58
What was the **theory of Jean-Baptiste Lamarck**?
**Changes that occur in organism during its lifetime can be inherited**
59
Which **book did Darwin propose his theory in**?
**On the Origin of Species 1859**
60
What is **evolution**?
**Change in inherited characteristics of population over time** through process of **natural selection** which may result in **formation of new species**
61
What does the **theory of evolution state all species evolved from**?
**Simple life forms** first **developed more than 3 billion years ago**
62
What is **speciation**?
**Over time, phenotype of organism changes so much** due to **natural selection** that **new species formed**
63
How are **2 new species formed**?
**2 populations of one species** become so **different in phenotype**, can **no longer interbreed to produce fertile offspring**
64
What is a **species**?
**Group of similar organisms** that can **reproduce** to give **fertile offspring**
65
What **2 things lead to speciation**?
**Isolation** and **natural selection**
66
What is **isolation**?
**Populations** of a **species** are **separated**
67
What is **isolation occurring due to**?
**Physical barriers**
68
How is a **new species developed** due to **physical barriers separating populations**?
**Environment different on each side, different characteristics** become more **common** in **each population** due to **natural selection operating differently** on populations
69
Who **independently proposed the theory of evolution by natural selection** and **published joint writings with Darwin** in **1858**?
**Alfred Russel Wallace**
70
What was **Alfred Russel Wallace best known for (2 things)**?
Work on **warning colouration in animals** and his **theory of speciation**
71
What **led to our current understanding of the theory of speciation (2 things)**?
**Observations of Alfred Russel Wallace**
**More evidence over time**
72
Who **carried out genetic experiments with pea plants** in the **mid 19th century**?
**Gregor Mendel**
73
What **3 important conclusions** did **Mendel reach about heredity in plants**?
1) **characteristics in plants determined by ‘hereditary units’**
2) **hereditary units** passed on to **offspring unchanged** from **both parents**, one unit from each parent
3) **hereditary units dominant** or **recessive**
74
Why did **scientists not understand Mendels findings until after his death**?
**Didn’t know about genes, DNA and chromosomes**
75
In the **early 20th century** what did **scientists observe about chromosomes**?
**chromosomes** and **Mendels ‘units’** behaved in **similar** ways, led to **idea ‘units’ (genes) located on chromosomes**
76
What did **scientists observe about chromosomes** in the **late 19th century**?
How **chromosomes behaved** during **cell division**
77
What did **scientists discover about genetics** in the **mid 20th century (2 things)**?
**Structure of DNA determined**
**Mechanism of gene function worked out**
78
Why is the **development of new antibiotics unlikely to keep up** with the **emergence of new resistant strains (2 reasons)** ?
**Costly** and **slow**
79
What is an **example of a ‘superbug’** ’ (resistant to most known antibiotics)?
**MRSA**
80
How are **antibiotic resistant strains formed** and **easily spread**?
**Mutations of bacteria produce new strains**
**Antibiotics resistant strains survive** and **reproduce, population rises**
**Spread** as **people not immune** and **no effective treatment**
81
What are **2 pieces of evidence** for **evolution**?
**Fossils**
**Antibiotic resistant bacteria**
82
What are **fossils**?
**Remains of organisms** from **millions of years ago**, found in **rocks**
83
What are **3 ways fossils** are **formed**?
1) **preservation** as one or more of **conditions needed for decay** are **absent**
2) **parts of organism replaced by minerals** as **decay**
3) **casts** and **impressions**
84
How are **casts** and **impressions** of an **organism formed**?
**Buried** in **soft clay**, **clay hardens** around **organism** as it **decays** leaving **cast**
85
What are **2 reasons scientists cannot be certain about how life began on earth**?
**Many early forms of life were soft bodied, left few traces**
**Fossils destroyed by geological activity**
86
How were **living things traditionally classified into groups**?
Depend on **structure** and **characteristics**
87
Who **developed** the **first classification system** in the **1700s**?
**Carl Linnaeus**
88
In the **Linnaean system** what are **living things first divided into**?
**Kingdoms**
89
What are **kingdoms subdivided into (6 things)** in the **Linnaean system**?
Phylum
Class
Order
Family
Genus
Species
90
Which **2 developments** led to **scientists putting forward new models of classification**?
Knowledge of **biochemical processes** inside organisms **developed**
**Microscopes improved**
91
Who **proposed** the **three domain system** of classification?
**Carl Woese**
92
What **evidence** did **Carl Woese** use to develop the **three domain system**?
**New chemical analysis techniques**
93
What are the **3 domains** organisms are divided into?
**Archaea**
**Bacteria**
**Eukaryota**
94
What are **archaea**?
**Primitive bacteria** living in **extreme environments**
95
What does **Eukaryota include (4 things)**?
Protists
Fungi
Plants
Animals
96
How are **organisms named**?
By **binomial system- genus** then **species**
97
What are **evolutionary trees**?
**Method** used by **scientists** show how believe **organisms are related**
98
What are **2 ways scientists work out evolutionary relationships**?
**Living organisms- current classification data**
**Extinct species- fossil data**
