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Bio yr 12 > MOD 5 HEREDITY > Flashcards

MOD 5 HEREDITY Flashcards

1
Q

sexual reproduction

A

the process of forming a new organism from the fusion of the offspring’s parent’s male and female gametes (fertilisation). Offspring that is formed are not genetically identical to either parent (variation).

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2
Q

asexual reproduction

A

the process of forming an offspring (usually a clone) from just one parent through cell division. No gametes are involved, much less variation, e.g. bacteria.

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3
Q

ANIMALS - SEXUAL REPRODUCTION: EXTERNAL FERTILISATION

A
  • Involves the fusion of gametes (egg and sperm) outside of the body of a parent e.g. aquatic animals when spawning such as salmon, the water acts as a medium which the gametes can travel.
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4
Q

EXTERNAL FERTILISATION + AND -

A

large amount of offspring
+ More genetic variation
+ Easier to find mates as gametes released can drift
- Many unfertilised gametes
- Lesser chance of survival for offspring
- Large amount of release of eggs and sperm = lots of energy used

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5
Q

INTERNAL FERTILISATION + AND -

A

more advantageous
+ embryo protected from predators
+ More selective of their mates
+ higher chance of survival for offspring
+ parental care after birth
- Only a few offspring can be produced at once
- More energy required
- Less offspring produced
- More energy to care for young

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6
Q

PLANTS SEXUAL REPRODUCTION

A

Flowers make up the reproductive organ in plants. Petals and nectar lure insects and animals to assist in delivery of pollen.
1. Male parts = filament and anther (together called stamens). Pollen produced in the anthers. Pollen grains are microscopic structures becoming the pollen tube and the generative cell that releases the sperm nuclei.
2. Female parts (carpel) = consists of the stigma, style, the ovary and egg cell (ovule).
3. Pollination = during pollination, the pollen grain reaches the sticky stigma. The pollen grains can be transferred to other flowers by wind, insect and animals.
4. Fertilisation = after landing on the stigma, a pollen tube grows down through the style into the ovary. The male gamete then moves down to try fertilise the ovum.

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7
Q

plants: cuttings

A

Asexual
the stalk is cut and planted where it will grow and turn into another plant e.g. used for roses and sugarcanes
- genetically identical

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8
Q

plants: runners

A

plants e.g. strawberry plants, develop stems extending from the plant and along the soil. Nodes develop along these which extend into soil resulting in a formation of new plant runners where a new plant can grow. The runner joins the new (genetically identical plant) to the parent plant

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9
Q

plants: bulbs

A

underground food storage organs that grow and develop into new plants. When a new plant forms, the bulb provides nutrients to plant for survival e.g. onions.
- genetically identical

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10
Q

Fungi: Budding

A

Asexual
in fungi e.g. yeast, one parent cells develops bud cell. Overtime the bud undergoes mitotic division whilst still attached to parent cell. It separates when independent enough to support itself, and undergoes further cell division producing more bud cells
- genetically identical

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11
Q

Fungi: Spores

A

Asexual
in mould and mushrooms there are microscopic cells that can form from meiosis or mitosis. Hyphae are fine, thread like structure that branch where the ends are capable of producing asexual spores. These are carried by the wind, then germinate to form genetically identical hyphae.

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12
Q

Bacteria reproduction

A

Asexual
Binary Fission: Starts with copying the genetic material (in the form of bacterial chromosomes) of the parent cell. No nuclear splitting occurs as no cell nucleus. Two daughter cells are genetically identical to each other and parent.

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13
Q

Protists: asexual reproduction

A

Protists/protozoa e.g. paramecium are single celled, eukaryotic organisms. They reproduce asexually by binary fission or budding.

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14
Q

Protists: sexual reproduction

A

Reproduce sexually by conjugation where the cells fuse together briefly to exchange nuclear material.

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15
Q

fertilisation and implantation in mammals

A

Egg released from ovary –> Sperm travels through vagina, and uterus to meet egg in the Fallopian tube –> Gametes fuse to form a zygote –> cell division occurs, then cells form a blastocyst where some cells become embryo or placenta–> blastocyst implants in uterus lining and cells continue dividing–> blastocyst divides until an embryo is formed in the uterus.

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16
Q

Human Chorionic Gonadotropin

A

produced by placenta, responsible for early pregnancy symptoms, increases after implantation, hormone detected in tests

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17
Q

Progesterone

A

maintains functionality of placenta, prevents contractions in uterus, as baby and placenta grow, need progesterone

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18
Q

Oestrogen

A

ovarian hormone controlled by luteinising hormone (LH) that triggers ovulation, helps development of the unborn baby e.g. maturation of lungs kidneys, stimulates breast growth and milk duct development, aids blood flow to foetus

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19
Q

Oxytocin

A

helps contraction of uterus, stimulates mammary glands, raised at labour

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20
Q

gene

A

Gene –> a discrete unit of hereditary information consisting of a specific section of DNA that stores info as a coded sequence – determine phenotypes

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21
Q

genotype

A

Genotype –> organism’s genetic makeup for a particular characteristic

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22
Q

DNA structure

A
  • DNA is a double helix made up of two strands of nucleotides held together by weak hydrogen bonds in the centre.
  • Each nucleotide consists of a phosphate group, a deoxyribose sugar, and a nitrogenous base attached to the sugar.
  • The four types of bases
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23
Q

Process of DNA replication

A

During mitosis and meiosis, it is necessary for the DNA to make an exact copy of itself.
Step 1: The DNA double helix is unwound and unzipped by the enzyme helicase.
Step 2: The DNA unzips forming two single strands
Step 3: Nucleotides are attached to the single strands resulting in two identical strands of DNA with the aid of the enzyme DNA polymerase.
Step 4: DNA fragments join together by forming bonds between nucleotides. With the aid of the enzyme DNA ligase
Step 5: The two double stranded molecules are now called chromatids and twist to form a double helix.

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24
Q

Mitosis

A
    • Cells need to grow and repair/replace cells and tissue
      INTERPHASE
      PROPHASE
      METAPHASE
      ANAPHASE
      TELOPHASE
      CYTOKINESIS
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25
Q

Meiosis

A
  • Process that produces gametes(eggs and sperm), 2 divisions, 4 haploid cells
    INTERPHASE
    PROPHASE I
    METAPHASE I
    ANAPHASE I
    TELOPHASE I AND CYTOKINESIS
    PROPHASE II
    METAPHASE II
    ANAPHASE II
    TELOPHASE II
    CYTOKINESIS
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26
Q

genetic variation in meiosis: crossing over

A

During prophase I arms of homologous chromosomes exchange genetic material causing the mixing of paternal and maternal genes and the result is a new combination of alleles on each chromatid, increasing genetic variation for the offspring.

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27
Q

genetic variation in meiosis : independent assortment

A

random alignment of homologous chromosomes during meiosis 1 which increases the number of possible combinations of chromosomes and increased genetic variation.

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28
Q

Genetic variation in meiosis: Random segregation

A

During anaphase I, one entire chromosome of each pair moves into a daughter cell. Referred to as random segregation, ensures the chromosome number in the resulting gametes will be half that of the original cell.

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29
Q

Prokaryotes DNA and polypeptide synthesis

A

Prokaryotes (bacterial cells) contain circular DNA in the cytoplasm known as plasmids
- Transcription and translation occur simultaneously in the cytoplasm
- DNA sequence Is not as repetitive
- Unbound DNA
- Smaller amount of DNA

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30
Q

Eukaryotes DNA and polypeptide synthesis

A

Eukaryotes, (including human cells), contain linear DNA found in the nucleus
- Some in mitochondria or chloroplasts
- DNA sequence more repetitive
- Does not contain plasmids
- Transcription occurs in nucleus, and translation occurs in the cytoplasm
- Larger amount of DNA

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31
Q

protein synthesis

A

DNA never leaves the nucleus and holds the original copy of instructions (must remain in nucleus), an intermediate molecule called messenger RNA (mRNA) is created to deliver the message to the ribosome for the instructions to be used to create a polypeptide.  two step process: transcription and translation

32
Q

Transcription in detail

A

In the nucleus, the enzyme RNA polymerase binds to a part of the double stranded DNA molecules causing it to unzip and the DNA code is transcribed into the single stranded mRNA molecule.
- Taking a copy of a section of a gene
- The sequence of nucleotide bases on the mRNA molecule is the same as the DNA coding strand, except that URACIL is complementary to A instead of T (NO T’S)

33
Q

translation in detail

A

The mRNA carries a transcribed copy of the relevant instructions from the nucleus to the ribosomes (outside of the nucleus) in the cytoplasm – through pore in nucleus.
- The ribosome moves along the mRNA molecule and attaches tRNA molecules by temporarily pairing the bases of the tRNA anticodons with their complementary triplet of bases/ codons on the mRNA
- A group of three bases codes for a specific amino acid –> peptide bonds form between amino acids – the amino acids are then split off their tRNA carrier –> mRNA and tRNA are recycled

34
Q

importance of mRNA

A

Role: to carry protein information from the DNA in a cell’s nucleus to the cell’s cytoplasm. mRNA holding the correct genetic information is essential so that it can be translated into the correct polypeptide chain, so the cell can function correctly. Therefore mRNA is very important in transcription.

35
Q

importance of tRNA

A

tRNA goes to the ribosome to attach their corresponding amino acids to the polypeptide chain in translation. Without tRNA, the mRNA sequence could not be converted into the correct sequence of amino acids, so the cell can function correctly. tRNA is therefore very important in translation. Allows the protein - folding process to occur.

36
Q

importance of polypeptide synthesis

A

Polypeptide synthesis provides the main component for proteins, and provides a mechanism for the production of critical proteins like specific enzymes, antibodies, and haemoglobin

37
Q

protein synthesis summary

A

The DNA is unzipped and a complementary mRNA strand is transcribed. The mRNA moves to the ribosomes where translation occurs. Each codon is matched to a tRNA molecule with a complementary anticodon and carries a specific amino acid. The amino acids are joined together to form a polypeptide/protein.

38
Q

WAYS IN WHICH THE ENVIRONMENT MAY AFFECT THE EXPRESSION OF A GENE IN AN INDIVIDUAL

A

appearance of individual not solely based on their genetic information
- e.g. Hydrangeas have different flower colour depending on the pH of the soil/ e.g. height of plants can be determined by different growth conditions

39
Q

Proteins

A

Proteins are large, complex macromolecules made up of one or more polypeptide chains. The encoded information in the cells DNA directs the production of the chains. These form particular proteins and each protein type carries out a particular function in the cell which ensures the cell develops a particular structure in keeping with the type of tissue to which it belongs.

40
Q

Four levels of protein structure

A

primary, secondary, tertiary, Quaternary

41
Q

primary structure of protein

A

The amino acid sequence of the polypeptide chain, held together by peptide bonds

42
Q

secondary structure of protein

A
  • Related to the way that each polypeptide chain will coil up into helixes (alpha helix) due to hydrogen bonds, by forming more hydrogen bonds between carboxyl and amine groups
43
Q

Tertiary structure of proteins

A
  • Related to the way that the coiled-up polypeptide chains further coils up to form an irregular three dimensional structure.
  • This is critical in providing the shape of the eventual protein which is critical for proteins function
  • E.g. ionic bonds, hydrogen bonds, disulfide bonds, hydrophilic interactions
44
Q

Quaternary structure of proteins

A
  • Related to the way different polypeptides interact with other polypeptides forming a functional protein e,g, an enzyme
  • This bonding between polypeptides involve hydrogen bonding
  • one or more together
45
Q

sex linked genes

A
  • They are physically linked to the sex chromosome
  • Males lack one X chromosome and only have one allele for each sex-linked gene (rather than a pair of alleles present in females)
  • e.g. red-green colorblindness is sex linked inheritance. The gene is carried on X chromosome, therefore males only need one allele, while females require two.
46
Q

mendelian inheritance

A

There are dominant and recessive alleles. The phenotype will reflect the dominant allele in heterozygous organisms. 2 possible phenotypes

47
Q

incomplete dominance

A

Both alleles for a trait are dominant. In heterozygous individuals, blending can occur. 3: 1 ratio, 3 dominant and recessive phenotypes

48
Q

co-dominance

A

Both alleles are dominant. In heterozygous individuals, both traits are expressed in the phenotype without blending. e.g. roan, human blood types O: OO - AB:AB - A: AA or AO – B:BB or BO

49
Q

polygenic

A

Trait is produced by many genes, many possible phenotypes

50
Q

features of dominant traits

A

If both parents are shaded, but they have an unshaded child = dominant

51
Q

features of recessive traits

A

If both parents are unshaded, but have a shaded child = recessive

52
Q

determining if sex linked

A
  • In sex linked traits, males are more commonly affected
  • cannot be passed from father to son
  • If a female has the trait, she will only pass it on to her son
53
Q

X linked dominant

A

Affected daughters must be from affected fathers (Dad –> Daughter –> Dominant DDD)

54
Q

X linked recessive

A

Affected sons from affected mothers (carriers)

55
Q

Polygentic inheritance

A
  • Human features like height, eye colour, and hair colour come in a lot of slightly different forms because they are controlled by many genes, each of which contributes some amount to the overall phenotypes
  • As the number of genes involved is increased, finer variations in eye, hair or height colour results.
56
Q

environmental effects

A
  • Human phenotypes also vary because they are affected by the environment e,g. weight can = diet and exercise not just genetics
57
Q
  • Single nucleotide polymorphism/ SNP
A
  • Single nucleotide polymorphism occurs where one nucleotide in the genome of an individual is different to the rest of the populations nucleotide at the same locus of the chromosome –> this is because due to SNP, a new nucleotide randomly replaced or substituted an existing nucleotide in the organism’s DNA sequence.
58
Q

SNP facts

A
  • Most SNP’s don’t have observable differences between people because many of the differences occur in the non-coding region of the DNA.
  • SNP versions from parents are inherited, matching with most close family
  • The number of SNPs where you match can be used to tell how closely related they are
59
Q

SNP effects

A
  • Single nucleotide polymorphism/ SNP can generate biological variation between people by causing differences in the genes coding for specific proteins which influence a variety of traits e.g. appearance, disease susceptibility, and response to drugs  SAVE TIME AND MONEY FOR PATIENTS–>
60
Q

Identify how a ‘SNP’ is different to a mutation

A

A SNP is a change in a single nucleotide of a genome, while a mutation is a broader term, to describe random changes in the structure of DNA.

61
Q

SNP analysis

A
  • Analysis of SNPs can be used to identify genetic markers associated with disease or traits
  • Reliable SNPs could serve as predictive markers that inform our decisions about numerous aspects of medical care e.g. specific diseases, effectiveness of various drugs and adverse reactions to specific drugs
  • This technique saves time, money, and discomfort for millions of patients through accurate diagnoses and matching patients with appropriate medication
62
Q

ASTHMA APPLICATION OF SNPs

A
  • The drug albuterol is commonly prescribed to relieve symptoms of asthma – it acts on a specific receptor of the lung cell that is encoded by a specific gene
  • Scientists have found 13 locations on this gene where SNPs exist –> people with asthma have unique SNP profiles –> response to medication varies
63
Q

Sanger sequencing

A

process of determining the sequence of nucleotides in a piece of DNA, uses the natural process of DNA replication to identify the precise order of nucleotides for the sequence of a DNA segment.

64
Q

DNA PROFILING

A

DNA profiling refers to the process of analyzing DNA variations for the purpose of identification (individuals can be identified)
- DNA sequences which are usually different in different people are called Genetic markers, regions of DNA that usually vary between individuals, these are used to construct DNA profiles, commonly used genetic markers e.g. Short tandem repeats and SNP’s

STR’s - a string of repeating nucleotide units e.g. CGA CGA CGA CGA, where the number of repeats varies between people, have no impact on health

65
Q

application of DNA profiling

A
  1. Determining parentage: A person’s DNA profile consists of a combination of parents alleles
  2. Identification: suspect/victim is a person whose DNA profile matches the one from the scene
66
Q
  1. FRAGMENTATION OF DNA USING RESTRICTION ENZYMES
A

DNA cut with specific restriction enzymes to generate fragments
- Restriction enzymes are like molecular scissors, they cut DNA into smaller sections
- Researchers use different restriction enzymes to target different sections of DNA they want to break up
- Restriction enzymes target differences/variations among people in their DNA
- This variation results in different size/lengths in DNA fragments

67
Q
  1. POLYMERASE CHAIN REACTION (PCR), also used in DNA sequencing
A
  • fragments are amplified using PCR
  • process makes millions of copies of a gene occurring outside the cell and involves amplifying specific DNA sequences by multiple cycles of replication, heating and cooling.
  • practical applications in forensics, genetic testing, and diagnostics

The basic steps are:
a) Denaturation (96°C): Heat the reaction strongly to separate or denature, the DNA strands. This provides single-stranded template for the next step.
b) Annealing: Cool the reaction so the primers can bind to their complementary sequences on the single- stranded template DNA.
c ) Extension (72°C): Raise the reaction temperature so Taq polymerase extends the primers, synthesizing new strands of DNA.

68
Q
  1. GEL ELECTROPHORESIS
A

The fragments are separated using gel electrophoresis and the resulting profiles are compared
- Process used by scientists where they place the DNA samples from the PCR into a gel and run an electric current through the DNA samples to separate and visualize DNA fragments according to their size
- fragments are attracted to the positive terminal of the machine
- Scientists analyse the rate at which the fragments move and analyse that information
- Shorter segments move farther away from their original location, larger segments stay closer
- The segments align in parallel row

69
Q

the use of population genetics data in conservation management

A
  1. calculate the risk of extinction –> by looking at genetic diversity and how animals can withstand environmental changes
  2. Monitoring inbreeding (closely related individuals breeding together) –> taking genetic samples and comparing genomes shows how closely related pop. members are + measure allele frequencies for unhealthy mutations as a result of inbreeding –> scientists can manage this.
  3. Investigating speciation –> comparing allele frequencies within and between populations determines the creation of new species/ if they no longer belong to a certain species
70
Q

population genetics studies used to determine the inheritance of a disease or disorder

A

Population dynamics is the study of genetic variation within and between populations used to measure allelic frequencies in a population, thus giving us an image of what number of alleles are being lost during evolution and what amount are being transferred through gene flow. can give us a rough image of the probabilities of inheritance disorders within a population.
- Genome wide association studies (comparing the genomes of people that have a specific genetic disease to those without) can be used to identify SNP’s which affect one’s chance of developing a genetic disease
- Identifying the regions of DNA associated with a genetic disorder shows us who is likely to be affected, what goes wrong in the cell to cause the disease and how to treat it.

71
Q

population genetics relating to human evolution

A

Anthropological genetics is the study of human population genetics –> Analysing DNA can inform us of evolutionary relationships e.g. find out when the last common ancestor of two species/populations lived which also can tell us the migration of species such as humans.
Population genetics attempts to resolve this question by examining the genetic variation and similarities in modern day humans.
* Humans share 98.8% DNA with chimpanzees and bonobos (closest living relatives).

72
Q

Mitosis steps

A
  1. DNA replicates, cell functions carried out
  2. DNA molecules condense into chromosomes, nuclear membrane starts breaking down
  3. chromosomes line up in middle of cell, spindle fibres attach to centromere
  4. sister chromatids pulled apart, move to opp sides of cell
  5. nuclear membranes reform
  6. cytoplasm divided into 2 daughter cell each containing same no. of chromosomes
73
Q

Meiosis steps

A
  1. DNA replicates, stage before
  2. chromosomes condense and align into homologous pairs, crossing over occurs
  3. homologous pairs line up in middle of cell, independent assortment occurs
  4. homologous pairs pulled apart to opp poles of cell
  5. nuclear membrane begins to reform around chromosomes, cytokinesis divides cytoplasm to 2 daughter cells
  6. chromosomes condense and nuclear membrane breaks down, spindles begin to attach
  7. spindles move chromosomes to middle of cell
  8. sister chromatids pulled apart to opp poles of cell
  9. nuclear membrane reforms around each set of chromosomes
  10. cytoplasm from both cells split into 2 again and now there are 4 haploid cells.
74
Q

DNA profiling steps

A
  1. Collect a DNA sample e.g. hair, saliva, blood
  2. Extract DNA from sample and separate it from other chemical e.g. proteins
  3. Amplify STR fragments using a PCR with primers which flank the STR region
  4. Determine the length of the STR fragments using gel/capillary electrophoresis
  5. Interpret the electrophoresis gel/electropherogram
75
Q

Sanger sequencing steps

A
  1. Collect a DNA sample obtained from any material which contains cells e.g. hair, saliva, blood
  2. Extract DNA from sample – Chemicals are added which break open the cells. DNA is separated from the other cell components.
  3. Amplify DNA – involves using PCR to make lots of copies of the DNA, only necessary if sample was too small.
  4. Perform Sanger sequencing reaction – separately identify the position of each nucleotide with the use of PCR’s
  5. Determine the DNA sequence – run all 4 PCR reactions on an electrophoresis gel to determine the lengths of the fragments in each reaction. DNA sequence determined by a computer
76
Q

Sanger sequencing applications

A
  1. Testing for genetic diseases and disorders.
  2. Biological research, at the molecular level.
  3. Providing evidence for evolution.
  4. Personal identification.

Bio yr 12 (2 decks)

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