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Biology cells > Reproduction Notes > Flashcards

Reproduction Notes Flashcards

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1
Q

What is asexual reproduction?

A
  • 1 parent
  • No gametes
    -No mixing of genetic information
    -Offspring are genetically identical (clones). These new cells are made by mitosis
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2
Q

What is sexual reproduction?

A

2 parents
Gametes are made by meiosis/ fertilisation of gametes/fusion of nuclei
Mixing of genetic material
Offspring shows genetic variation

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3
Q

How do your body cells divide?

A

They pairs of chromosomes that divide asexually by mitosis

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4
Q

How do cells in reproductive organs divide?

A

By meiosis to produce gametes which have single sets of chromosomes (haploid). These are not genetically identical

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5
Q

How do cells divide by meiosis?

A

-Copies of the genetic information are made
- cell divides twice to form 4 gameteswith a single set of chromosomes . These gametes are all genetically different

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6
Q

What happens when gametes join at fertilisation?

A

Male and female gametes fuse to form a zygote which is a diploid and divided by mitosis to form an embryo. The cells differentiate and become specialised to perform particular functions

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7
Q

Advantages of asexual reproduction

A

-Only 1 parent needed
-More time and energy efficient as you do not need to find mate
-Faster than sexual reproduction
-Many identical offspring can be produced when conditions are favourable/stable

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8
Q

Disadvantages of asexual reproduction

A

-Limited genetic variation in population : genetically identical to parents
-Disease affects whole population because of no genetic variation
-Population only suited to one habitat

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9
Q

Advantages of sexual reproduction

A

-production genetic variation in offspring
- if environment changes variation gives a survival advantages to species by natural selection
- Natural selection can be speeded up by humans in selective breeding to increase food production
-Disease less likely to affect population due to variation

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10
Q

Disadvantages of sexual reproduction

A

-Slower process requiring more energy
Difficult for isolated members to reproduce

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11
Q

How do fungi reproduce?

A

-Asexually and sexually
Species of fungi release spores that can develop into fungi either way
Spores that are produced via sexual reproduction show variation

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12
Q

How do plants reproduce?

A

Can produce seeds via sexual reproduction
Strawberry plants produce runners which form identical offspring
Daffodils reproduce by bulb division which grow into new identical offspring

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13
Q

How do malaria reproduce?

A

Parasites produce asexually in human and sexually in the mosquito

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14
Q

What is the genome?

A

The entire set of a genetic material of an organism

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15
Q

What is DNA?

A

The genetic material in the nucleus contained in structures called chromosomes

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16
Q

Describe the structure of DNA

A

Polymer made up two strands forming a double helix . It is a polymer made of monomer units called nucleotides. Outer backbone is formed of alternating sugar and phosphate groups and bases are found on the inside of the molecule by complementary base pairing. This double stranded molecule is twisted to from a double helix.

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17
Q

What is a gene?

A

A segment of DNA on a chromosome which codes for a particular sequence of amino acids . They control our characteristics

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18
Q

How will knowledge of the human genome be of use in the future?

A
  1. Search for genes linked to different type of diseases
  2. Understanding and treatment of inherited disorders
  3. Use in tracing human migration patterns from the past wha
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19
Q

What is a nucleotide?

A

Common sugar
Phosphate group
One of four bases attached to sugar

20
Q

What are the 4 different bases?

A

Adenine
Cytosine
Thymine
Guanine

21
Q

What are the base pairs?

A

A-T
C-G
This is known as complementary base pairing and forms the backbone

22
Q

Coding for amino acids

A

A sequence of three bases is the code for a particular amino acids to form a particular protein.

23
Q

Describe protein synthesis

A

Proteins are made in the cytoplasm on ribosomes
A gene produced a template witch complementary bases in the DNA and can leave the nucleus
This binds to a ribosome in the cytoplasm
Carrier molecules are attached to a specific amino acid and attach themselves to the template in the order given by the DNA
The amino acid sequence joins to form a specific protein
Carrier molecules keep bringing specific amino acids in correct order until template e is completed
The protein detached from carrier molecules and carrier molecules detach from the template and return to cytoplasm to pick-up more amino acids.
When the chain is completed molecule fold to form unique shape which enables it to carry out is function

24
Q

What effect would a change in the sequence of bases in a gene have on the protein formed?

A

It will change the sequence of amino acids in your protein which changes the shape that the protein folds into meaning it may not function in the same way

25
Q

What do each triplet of bases do?

A

Codes for a specific amino acids which is read by the ribosome to form a protein

26
Q

What type of proteins are there?

A

Enzymes —> Biological catalysts
Hormones —> Carry messages around the body
Structural proteins —> provide structure and are physically strong

27
Q

What are mutations?

A

Random changes that occur in the sequence of DNA bases

28
Q

Explain mutations in coding DNA

A

Does not alter the protein or only slightly so that the function and appearance is not changed

29
Q

What is non coding DNA

A

DNA switches genes on and off . Mutations in this DNA do not directly affect phenotype but can effect which genes are on and off

30
Q

What are the effects of mutations?

A

Do not alter the protein on only slightly so appearance or function isn’t changed
Some code for an altered protein with a different shape
Which can effect ability to carry function like shape of active site of enzyme changes and substrate can no longer bind to active site

31
Q

What is gene switching?

A

Not all parts of the DNA code for proteins so some non coding parts can switch genes on and off.
If there is mutation in a section of non coding DNA which controls gene expression they may be altered or not expressed at all

32
Q

What is a gene?

A

A section of DNA which determines a particular characteristic and provides genetic code for 1 protein

33
Q

What is an allele?

A

The alternative form of the same gene

34
Q

What is a dominant allele?

A

An allele which is always expressed even if only one copy is present

35
Q

What is a recessive allele?

A

An allele which is only expressed if two copies are present (so no dominant allele)

36
Q

What does homozygous mean?

A

When the alleles are the same e.g DD,dd

37
Q

What does heterozygous means?

A

When the alleles are different Dd

38
Q

What is a genotype?

A

The pairs of alleles for a characteristic

39
Q

What is a phenotype?

A

The expression of the genotype

40
Q

What is polydactyly?

A

Genetic disorder that causes someone to be born with extra fingers or toes
A dominant allele
Even if one parent is carrier disorder can be inherited

41
Q

What is embryo screening?

A

When foetuses in the uteri and embryos by IVF can be screened for allele that cause genetic disorders

42
Q

What is CVS?

A

Chorionic villus-part of placenta
Done between 10 and 12 weeks
Small sample taken from developing placenta which provides cells from foetus that can be screened and you extract the DNA to be tested for genetic disorders

43
Q

What is amniocentesis?

A

Carried out between 15 and 16 weeks
Needle placed through abdomen and fluid collected
Developing foetus sheds cells into amniotic fluid
DNA isolated from cells and screened for genetic disorders

44
Q

What is PGD?

A

Stimulate ovaries to produce as many cells as possible
Harvest eggs
Fertilise them in vitro
Allow them to grow into embryos by mitosis
At embryonic stage remove cells from embryos,isolate the DNA and screen to see if it has the allele for a genetic disorder
If healthy implant into mother

45
Q

Advantages of embryo screening

A

Parents make informed decision to continue with pregnancy or not
Children won’t inherit or suffer from genetic disorder when born
Ensures genetic disorder is not passed onto future generations
Less expensive to NHS, cheaper in long run to treat children with genetic disorder
-Expensive to parents so can prepare financially and emotionally
Can avoid suffering

46
Q

Disadvantages of embryonic screening

A

Immoral to kill embryos regardless if they have genetic disorder or not, they have right to life
Potential harm to embryo, risk of miscarriage
Risk to mother’s health from procedure
Very expensive and not available to all
Pregnancy is terminated
Potential life destroyed is alleles causing genetic disorder are found in its genes during IVF

Biology cells (2 decks)

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