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Human Biology ATAR > chapter 13 > Flashcards

chapter 13 Flashcards

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1
Q

genes

A

sections of DNA that contain genetic code. store information that determines the activities and structure of the cell
consists of up to 1000 bases, possibilities are enormous

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2
Q

chromosomes

A

dna strands are bound to proteins called histones. each DNA is coiled around the histones so long molecules can fit into a small space
when a cell is about to divide, the coiled chromatin becomes even more tightly coiled to form chromosomes

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3
Q

DNA

A

deoxyribonucleic acid found in nucleus of the cell

contain genetic information that determines the structure of a cell and how it functions

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4
Q

steps of DNA replication

A
  1. double stranded DNA molecule unwinds and units by helicase (enzyme), and weak hydrogen bonds are broken
  2. primase is required to initiate/start replication. The primer helps DNA polymerase to know where to start copying
  3. DNA polymerase: binds to a single strand and helps create/build a complementary strand (using free nucleotides in nucleus) to know where to start copying
  4. ligase is needed to glue/seal DNA fragments together
  5. the DNA molecule is formed has one strand of the original parent DNA and 1 newly made strand
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5
Q

transcription

A
  1. takes place in the nucleus
  2. triggered by hormone that enters nucleus and binds to specific gene on DNA
  3. RNA polymerase then attaches to begin the process
  4. helicase makes the double stranded DNA molecule unzip to allow one of the DNA strands to be decoded (template strand)
    RNA polymerase transcribes the bases on the template strand to make a complementary molecule of mRNA (uracil)
  5. mRNA nucleotides floating around in the nucleus find their complement on the DNA strand and bond to gather due to base pair rule
    sequence of bases tell RNaA polymerase to stop copying this release mRNA molecule
  6. once the DNA segment has been copied by the mRNA bases, the mRNA strand separates from the DNA. mRNA contains complementary base sequence to original DNA
  7. introns are removed (Junk DNA)
  8. the mRNA leaves the nucleus via pore and enters the cytoplasm. it attaches to a ribosome for protein synthesis
  9. DNA zips up again to create the original double helix
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6
Q

translation

A
  1. takes place at a ribosome
  2. mRNA is read 3 codons at a time.
    AUG is the start codon, ribosome start making protein, methionine can be removed later
  3. tRNA delivers AA to the ribosomes, each tRNA carries a specific AA. the tRNA anticodon, will match with its complementary mRNA codon
  4. ribosome works its way down the strand of mRNA reading off the code. (tRNA is recycled, bringing in more AA) rRNA join AA together by forming a peptide bond
  5. as process continues, polypeptide chain is formed until a stop codon
  6. multiple copies of proteins are made as other ribosomes copy the first ribosome
  7. mRNA is recycles, broken up and nucleotides reused
  8. after translation, proteins are modified by folding and shortening them in a certain way (enzymes) transported to where the body needs
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7
Q

chromatin

A

in a cell that isn’t dividing, coiled DNA form an untangled network called chromatin

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8
Q

dna structure

A

building blocks are called nucleotides
each DNA consists of two strands of alternating sugars and phosphates with pairs of nitrogenous bases forming cross links between sugar molecules in the two strands
twisted into spiral shape (double helix)
base contains nitrogen atoms, bond between bases are weak hydrogen bonds

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9
Q

replication of DNA in interphase

A

two linked chains in DNA separate because bond between bases is weak
each separated sections half of the original and acts as a template for for nucleotides that form the other half using complementary bases

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10
Q

protein synthesis

A

amino acids joined to form chemical bonds that hold, AA together
joined in ribosome in cytosol of cell. DNA is too big to leave the nucleus so mRNA is used as it is small enough to go through nuclear pores
conversion of genetic code carried by DNA to an end product (protein)

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11
Q

genetic code

A

types of protein a cell makes is determined by it gens.
different genes are activated in different cells (insulin)
triplet codes for amino acids that are joined together at ribosomes

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12
Q

nucleosome

A

8 part histone structure

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13
Q

karyotype

A

photograph of chromosome organised by size shape and banding

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14
Q

lipid and carbohydrate synthesis

A

no genes to carry out instructions

made by enzymes (proteins) indirectly controlled by genes

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15
Q

mitochondrial DNA

A

in mitochondria
small circular molecules
has 37 genes
24 genes code for making tRNA molecules, 13 genes are instructions for making enzymes needed to make ATP
provides information which is needed for mitochondria to function

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16
Q

mitochondria

A

cells and mitochondria are codependent
inherited from mother as mDNA in sperm are destroyed in fertilisation
used for ancestry, evolution and forensics
disease: inability to produce sufficient energy to carry out simple tasks

17
Q

epigenetic

A

study of changes in gene activity that don’t involve changes in gene code
epigenome: second set of instructions that interact with DNA that activate/suppress expression of certain genes
exposure to certain stimuli can change epigenome

18
Q

acetylation

A

add acetyl group

cause DNA to unwind enhancing gene expression

19
Q

methylation

A

adding a methyl group

cause DNA to coil more tightly silences or switches of gene

20
Q

cell cycle

A

G1 phase: first growth, cells produce new proteins, grows and carries out its normal tasks
S phase: synthesis, DNA duplicates itself
G2 phase: second growth, short phase that involves preparation for cell division
M phase: mitotic, cell divides into two daughter cells

some cells leave cell cycle and stop dividing for years or rest of life. G0

21
Q

interphase

A

period between nuclear divisions
G1,S,G2
DNA replicates

22
Q

prophase

A

centrioles become visible early on, move to opposite ends of cell (poles) and microtubules radiate from them form framework of fibres called spindle
nucleolus disappears and nuclear membrane breakdown
chromatin threads of DNA coil to be seines chromosomes (2 chromatid joined at centre with centromere)
chromatids are identical to each other and tightly coiled
coiling makes it easier to distribute DNA to daughter cell
migrate to equator of cell

23
Q

metaphase

A

chromatid line up at equator

centromere of each pair is attached to a spindle fibre

24
Q

anaphase

A

each pair of chromatids separate at centromere

new chromosomes are pulled apart towards opposite poles of cell

25
Q

telophase

A

two sets of chromosomes form tight groups at each pole
nuclear membrane forms around each group and nucleolus appears
spindle fibres disappear
chromosomes gradually uncoil to become chromatin

26
Q

cytokinesis

A

while telophase occurs, cytoplasm begins to divide

furrow develops between two nuclei and deepens til it is cut in two

27
Q

joined at centromere =

A

chromatid

not chromosomes

28
Q

cancer

A

all cancers have common characteristics
when a tumour results form uncontrolled division of cells, don’t differentiate so the cancer cells can be identified
malignant: cells spread throughout the body
benign: don’t spread to other parts of body but can press on surrounding tissues
carcinogen: factors that can trigger cancer (UV, Xray, HPV, ionising radiation, chemicals)

29
Q

cervical cancer

A

caused by HPV, transmitted through genital skin contact during sex
Pap test: cells from cervix detect changes in cells that may develop into cancer

30
Q

breast cancer

A

mammogram: Xray picture that detects tumours, even really small ones

31
Q

bowel cancer

A

in large intestine
FOBT faecal occult blood test: detects traces of blood caused by polyps/ cancer. polyps can lead to cancer
Colonoscopy

32
Q

prostate cancer

A

no screening
DRE, digital rectal examination: feeling prostate for irregularities
PSA, prostate specific antigen:checks blood for a specific protein produced by prostate gland rising levels can indicate tumour
biopsy: small sample of tissue that can be checked for cancer cells

Human Biology ATAR (23 decks)

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