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REPRODUCTION Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is asexual reproduction?

A

Involves one parent.
The cells divide by mitosis.
No mixing of genetic information.
No variation in the offspring.

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2
Q

What is similar between the offspring and parents after asexual reproduction?

A

Asexual reproduction gives rise to genetically identical offspring known as clones. Their genetic material is identical to both the parent and each other.

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3
Q

Give examples of organisms that reproduce asexually?

A 
Fungi 
Bacteria 
Daffodils
Strawberries
Brambles.
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4
Q

What is sexual reproduction?

A

Involve a male and female sex cell from two parents. The sex cells (gametes) fuse together to form a zygote, which goes on to develop into a new individual.

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5
Q

How are gametes formed?

A

Meiosis.

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6
Q

Why is there variation among sexually produced offspring?

A

They inherit genetic information from both parents.

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7
Q

What are the gametes in plants?

A

The egg cells and pollen.

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8
Q

What are the gametes in animals?

A

The egg cells (ova) and sperm.

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9
Q

What is meiosis?

A

Cell division that takes place in the reproductive organs of animals and plants. In humans, these organs are the ovaries and testes. Meiosis results in sex cells, called gametes, which have only half the original number of chromosomes.

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10
Q

What happens when a cell divides to form gametes?

A

The genetic information is copied so there are four sets of each chromosome instead of the normal two sets. Each chromosome forms a pair of chromatids. This is very similar to mitosis.

The cell then divides twice in quick succession to form four gametes, each with a single set of chromosomes.

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11
Q

How is variation introduced to the gametes?

A

Each gametes produced is genetically different from all the others. Gametes contain random mixtures of the original chromosomes. This introduces variation.

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12
Q

How many chromosomes does a sex cell have?

A

23

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13
Q

How many chromosomes does a human body cell have?

A

46 (23 pairs)

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14
Q

What happens as an embryo develops?

A

Cells differentiate to form different tissues, organs, and organ systems.

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15
Q

What happens during asexual reproduction?

A

The offspring are produced as a result of mitosis from the parent cell. They contain exactly the same chromosomes and the same genes as their parents. There is no variation in genetic material.

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16
Q

How does sexual reproduction introduce variation?

A

The gametes are produced by meiosis in the sex organs of the parents. This introduces variation as each gamete is different. Then, when the gametes fuse, one of each pair of chromosomes, and so one of each pair of genes, comes from each parent, adding more variation.

The combination of genes in the new pair of chromosomes will contain different forms of the same alleles from each parent. This also helps to produce variation in the characteristics of the offspring.

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17
Q

What are some advantages of asexual reproduction?

A

Only one parent is needed. This is time and energy efficient as there is no need to find a mate or spread gametes. Often faster than sexual reproduction, rapidly producing large numbers of identical offspring.

Can be sped up by humans to produce large numbers of clones, for example to increase food production.

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18
Q

What are some disadvantages of asexual reproduction?

A

If the environment changes, then asexual reproduction is a disadvantage. If one organism cannot survive, then none can.

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19
Q

What is an advantage of sexual reproduction?

A

Provides variation in the offspring. If the environment changes, this variation gives a survival advantage as some offspring will be able to survive and reproduce. This is natural selection.

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20
Q

How does fungi reproduce asexually?

A

The fungal spores are produced by mitosis and they are genetically identical to the parent.
Made of thin threads called hyphae that together form the structures we can see.

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21
Q

How does fungi reproduce sexually?

A

Two hyphae from different fungi join and the nuclei fuse so the new hypha has two sets of chromosomes. It undergoes meiosis to make haploid spores, each with only one set of chromosomes which are different from the original hyphae. Some of the spores may produce fungi better adapted to survive the adverse conditions.

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22
Q

How do plants reproduce sexually?

A

The flowers contain the organs of sexual reproduction. The gametes - the pollen and the egg cells - are produced using meiosis. The pollen from one flower must reach the female parts of another flower in the process of pollination. Once the pollen has fused with the egg cell, seeds are formed. Sexual reproduction introduces variation and enables plants to survive as conditions change through natural selection.

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23
Q

How can plants reproduce asexually?

A

A new plant grows as a result of specifically directed mitosis.

24
Q

Give examples of plants that reproduce asexually?

A

Tiny new plants that form on the end of specialised stems called runners eg strawberry plants and spider plants.
Division of bulbs in plants such as daffodils.

25
Q

Explain asexual and sexual reproduction in malaria parasites.

A

Malaria parasites reproduce asexually in the human liver and blood cells. When the mosquito takes her blood meal, the drop in temperature between the human body and the mosquito triggers sexual reproduction in some parasites inside the red blood cells. There is a 20 minute window when sexual forms develop, burst out of the blood cells, and meet to form zygotes with two sets of chromosomes. These zygotes then undergo meiosis to produce new asexual parasites that will infect a new human host. The parasites show a lot of variation.

26
Q

What are your chromosomes made of?

A

Made up of a long molecule called DNA.

27
Q

What is DNA?

A

A polymer, a long molecule made up of repeating units. These very long strands of DNA twist and spiral to form a double helix structure.

28
Q

What are genes?

A

Small sections of the DNA. This is where the genetic information - the coded information that determines inherited characteristics - is actually stored.

Each genes codes for a particular sequence of amino acids to make a specific protein. These proteins include the enzymes that control your cell chemistry.

29
Q

What do the genes control?

A

The genes control the proteins, which control the makeup of the different specialised cells that form tissues. These tissues then form organs and organ systems that make up the whole body.

30
Q

What is the genome of an organism?

A

The genome of an organism is the entire genetic material of the organism. That includes all of the chromosomes, and the genetic material found in the mitochondria as well.

31
Q

Explain the mitochondria in terms of DNA.

A

Mitochondria contain their own DNA. You always inherit your mitochondria DNA from your mother because it comes from the mitochondria in the egg.

32
Q

How many base pairs does the human genome contain?

A

3 billion base pairs

33
Q

How many genes that code for proteins does the human genome have?

A

21000 genes that code for proteins.

34
Q

What does sequences the genomes of bacteria and viruses do?

A

Allows us to identify the cause of disease very rapidly and to choose the correct treatment.

35
Q

Why is it important to understand the human genome?

A

Helps us to understand inherited disorders such as cystic fibrosis and sickle cell disease. A better understanding can mean a higher chance of overcoming them either through medicines or by repairing faulty genes.

Plays a massive part in the search for genes linked to different types of diseases. Can make predicting the risk to an individual easier, so they can make lifestyle choices to help reduce the risks.

Helps us to understand human evolution and history. People all over the world can be linked through patterns in their DNA, allowing humans to trace human migration patterns from our ancient history.

36
Q

Where are proteins synthesised?

A

in the cytoplasm of the cell and the ribosomes.

37
Q

What letters represent the bases on DNA?

A

A, C, G and T.

38
Q

What is a nucleotide?

A

The combination of a sugar, a phosphate, and a base is called a nucleotide. The DNA molecule is made up of repeating nucleotide units.

39
Q

What are the long strands of your DNA made of?

A

Alternating sugar and phosphate section.

40
Q

How are the nucleotide units grouped?

A

The nucleotide units are grouped into three, and each group of three bases codes for a particular amino acid. Each gene is made up of hundreds and thousands of these bases.

41
Q

What does the order of the bases control?

A

The order in which the amino acids are assembled to produce a particular protein for use in your body cells.

Each gene codes for a particular combination of amino acids, which make a specific protein.

42
Q

What can a change or mutation in a single group of bases lead to?

A

A change or disruption to the whole protein structure and the way that it works.

43
Q

What are the base pairs?

A

C and G
T and A

These hold the structure of the DNA double helix together.
Key in the way the information from the genes on the DNA is translated into proteins in the cell.

44
Q

How are proteins made?

A

Protein synthesis.

45
Q

What is the first stage of protein synthesis called?

A

Transcription

46
Q

What is transcription?

A

The first stage of protein synthesis.

Takes place in the nucleus.
The base sequence of the gene is copied into a complementary template molecule. Scientists call this template messenger mRNA.
Messenger RNA is a single stranded molecule that passes out of the nucleus and into the cytoplasm.

47
Q

What is the second stage of protein synthesis called?

A

Translation

48
Q

What is translation?

A

The second stage of protein synthesis.

Takes place in the cytoplasm.
The mRNA molecule attaches to a ribosome. Amino acids are brought to the ribosomes on carrier molecules.
The carrier molecules are called transfer RNA (tRNA)

The ribosome reads the triplets of bases on the mRNA and uses this to join together the correct amino acids in the correct order.

Once the protein chain is complete, it then folds into its unique shape. The shape enables its job.

49
Q

What i the order of amino acids in a protein determined by?

A

The sequence of bases in the gene for that protein.

50
Q

How will a cell read a DNA sequence?

A

As triplets of bases. Each triplet encodes for a specific amino acid in the protein.

51
Q

What are alleles?

A

Versions of a gene

52
Q

What does the genotype of a person tell us?

A

The alleles present. It tells us the characteristics caused by the person’s alleles.

53
Q

What does homozygous mean?

A

A person has two copies of the same allele.

54
Q

What does heterozygous mean?

A

The person has two different alleles.

55
Q

When will a recessive allele show in the phenotype?

A

If two copies are present.

56
Q

When will a dominant phenotype show in the phenotype?

A

It will show even if only one copy is present.

57
Q

What is cystic fibrosis?

A

A disorder of cell membranes.

Biology (47 decks)

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